System, method and apparatus for non-mechanical optical and photonic beam steering

ABSTRACT

An example system includes a high-side electrode layer having a first number of electrical members alternated with, and electrically coupled to adjacent ones of a second number of electrical members, where either the first number of electrical members or the second number of electrical members are discrete electrodes, and the other one of the first or second number of electrical members are resistors. Accordingly, the high-side electrode layer is formed from alternating discrete electrodes and resistors. The example system further includes a low-side electrode layer, and an electro-optic (EO) layer having an EO active material at least partially positioned between the high-side electrode layer and the low-side electrode layer, thereby forming a number of active cells of the EO layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Pat. Application No. 18/088,369 (EXCT-0009-U01), filed 23 DEC 2022, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING”.

U.S. Pat. Application No. 18/088,369 is a continuation of International Application No. PCT/US2021/027986 (EXCT-0009-WO), filed on 19 APR 2021, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING”, now published on 6 JAN 2022 as WO 2022/005554.

International Application No. PCT/US2021/027986 is a continuation-in-part of U.S. Pat. Application No. 16/999,815 (EXCT-0003-U01-G), filed on 21 AUG 2020, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING.” International Application No. PCT/US2021/027986 is a continuation-in-part of U.S. Pat. Application No. 16/916,731 (EXCT-0004-U01), filed on 30 JUN 2020, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING”, now issued on 27 APR 2021 as U.S. Pat. No. 10,989,982. International Application No. PCT/US2021/027986 is a continuation-in-part of International Application No. PCT/US2020/064071 (EXCT-0006-WO), filed on 9 DEC 2020, and entitled “SYSTEM, METHOD, AND APPARATUS TO STEER AN ELECTROMAGNETIC BEAM UTILIZING STAGED STEERING.”

U.S. Pat. Application No. 16/999,815 (EXCT-0003-U01-G) is a continuation of International Application No. PCT/US2019/023915, filed 25 MAR 2019, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0003-WO). International Application No. PCT/US2019/023915 (EXCT-0003-WO) claims priority to U.S. Provisional Pat. Application No. 62/749,487, filed on 23 OCT 2018, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0002-P01). International Application No. PCT/US2019/023915 (EXCT-0003-WO) also is a continuation-in-part of, U.S. Pat. Application No. 15/796,055, filed on 27 OCT 2017, entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0001-U01), now issued on 24 NOV 2020 as U.S. Pat. No. 10,845,671.

U.S. Patent Application No. 16/916,731 (EXCT-0004-U01), filed 30 JUN 2020, is a continuation of International Application No. PCT/US2019/57616, filed 23 OCT 2019, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0004-WO). PCT/US2019/57616 (EXCT-0004-WO) claims priority to U.S. Provisional Patent Application No. 62/868,286, filed on 28 JUN 2019, entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0005-P01). International Application No. PCT/US2019/57616 (EXCT-0004-WO) also claims priority to U.S. Provisional Patent Application No. 62/749,487, filed on 23 OCT 2018, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0002-P01). International Application No. PCT/US2019/57616 (EXCT-0004-WO) also is a continuation-in-part of PCT/US2019/023915, filed 25 MAR 2019, and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING” (EXCT-0003-WO).

International Application No. PCT/US2020/064071 (EXCT-0006-WO) claims priority to U.S. Provisional Application 62/945,720, filed on 9 DEC 2019, and entitled “ELECTRO-OPTICAL (EO) BEAM STEERING TO A VERY WIDE ANGLE (>+/- 60°)” (EXCT-0006-P01). International Application No. PCT/US2020/064071 (EXCT-0006-WO) also is a continuation-in-part of, U.S. Pat. Application No. 16/999,815, filed on 21 AUG 2020 (EXCT-0003-U01-G), and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING.” International Application No. PCT/US2020/064071 (EXCT-0006-WO) also claims priority to, and is a continuation-in-part of, U.S. Pat. Application No. 16/916,731, filed 30 JUN 2020 (EXCT-0004-U01), and entitled “SYSTEM, METHOD AND APPARATUS FOR NON-MECHANICAL OPTICAL AND PHOTONIC BEAM STEERING”, now issued on 27 APR 2021 as U.S. Pat. No. 10,989,982.

Each of the foregoing applications is incorporated herein by reference in the entirety for all purposes.

BACKGROUND

Previously known beam steering systems and methods suffer from a number of drawbacks. Mechanically steered systems have a number of moving parts, manufacturing cost and complexity, and have limitations in the response time of the system to effect a beam steering change. Additionally, mechanical systems suffer from reliability issues related to mechanical failures. Previously known beam steering systems without mechanical steering additionally suffer from a number of drawbacks, including limited steering capability, limited steering efficiency, and high voltage differences occurring within the devices.

Operations of a typical previously known beam steering system are described following a previously known beam steering system includes a film of optically active material positioned between a ground electrode and discrete electrodes with voltages applied. The voltages start from zero, increase to a designed voltage over a number of electrodes, and then reset to zero. The discrete electrodes are separated by a spacing distance, which may be the same throughout the aperture (i.e., across the entire film). The designed voltage will be V_lambda, or the voltage sufficient to provide one optical path difference (OPD) of one wavelength, and will depend upon the properties of the film and the incident wavelength being steered. The voltages applied between adjacent discrete electrodes will be progressive, depending upon how many discrete electrodes are utilized to progress from zero voltage to the V_lambda, except between reset electrodes. At the reset electrodes, the voltage difference would be approximately V lambda - with a V_lambda voltage on a last discrete electrode of one progression, and approximately zero voltage on a first discrete electrode of the next progression, with a separation of 2πn before and after reset. The applied electric field is not confined between each discrete electrode and the ground electrode, and further the applied electric field is not parallel outside of the spacing between each discrete electrode and the ground electrode. Accordingly, previously known beam steering systems experience an edge effect and a fringing field causing large steering efficiency losses at the reset position, where the voltage cannot reset sharply to 0 V. The distance required to reset to zero is the flyback distance, which can be large in previously known beam steering systems, and can extend across several electrode widths.

Accordingly, improvements in beam steering systems, including systems with limited or no mechanical moving parts, are desirable.

SUMMARY OF THE DISCLOSURE

An example system includes a high-side electrode layer having a first number of electrical members alternated with, and electrically coupled to adjacent ones of a second number of electrical members, where either the first number of electrical members or the second number of electrical members are discrete electrodes, and the other one of the first or second number of electrical members are resistors. Accordingly, the high-side electrode layer is formed from alternating discrete electrodes and resistors. The example system further includes a low-side electrode layer, and an electro-optic (EO) layer having an EO active material at least partially positioned between the high-side electrode layer and the low-side electrode layer, thereby forming a number of active cells of the EO layer.

Certain further aspects of the example system are described following, any one or more of which may be present in certain embodiments. An example system includes where the high-side electrode layer terminates in a resistor at one or both ends of the layer, and/or where the high-side electrode layer terminates in an electrode at one or both ends of the layer. An example system includes a controller having a steering request circuit that interprets a steering request value, a steering configuration circuit that determines a number of EO command values in response to the steering request value, and where the number of EO command values correspond to a half-wave voltage profile. The example controller further includes a steering implementation circuit that provides a number of voltage commands in response to the number of EO command values. An example system includes the electrodes of the high-side electrode layer responsive to the number of voltage commands. An example half-wave voltage profile includes a first voltage value for a last electrode of a first phase delay progression, and a second voltage value for a first electrode of a second phase delay progression, where the first voltage value and the second voltage value have opposite signs. In a further embodiment, the first voltage value and the second voltage value have equal magnitudes. In certain embodiments, the voltage values having equal magnitudes includes the voltage values differing, within a noise voltage value, by a voltage difference corresponding to a π phase delay, and/or an nπ phase delay. An example nπ phase delay includes n having an integer value between 1 and 4, inclusive. An example system includes the voltage values having an opposite sign relative to a nominal voltage. An example system includes the first voltage value and the second voltage value symmetrically distributed about a 0π phase shift. An example low-side electrode layer includes a number of discrete electrodes. An example low-side electrode layer includes a continuous electrode. An example low-side electrode layer includes a reflective layer - for example formed using a reflective electrode, and/or using a reflective layer coupled to the low-side electrode layer.

An example apparatus includes a thin beam steering device, having a high-side electrode layer including a first number of electrical members alternated with, and electrically coupled to adjacent ones of a second number of electrical members. One of the first number or second number of electrical members are discrete electrodes, and the other one of the first number or second number of electrical members are resistors. The thin beam steering device further includes a low-side electrode layer and an EO layer having an EO active material at least partially positioned between the high-side electrode layer and the low-side electrode layer, thereby forming a number of active cells of the EO layer. The example apparatus includes a convex lens portion optically coupled to the thin beam steering device on a first side of the thin beam steering device, and a concave lens portion optically coupled to the thin beam steering device on a second side of the thin beam steering device.

Certain further aspects of the example apparatus are described following, any one or more of which may be present in certain embodiments. An example apparatus includes a controller having a steering request circuit that interprets a steering request value, and a steering configuration circuit that determines a number of EO command values in response to the steering request value, where the number of EO command values correspond to a half-wave voltage profile. The example controller further includes a steering implementation circuit that provides a number of voltage commands in response to the number of EO command values. An example thin beam steering device includes the high-side electrodes responsive to the number of voltage commands. An example half-wave voltage profile includes a first voltage value for a last electrode of a first phase delay progression, and a second voltage value for a first electrode of a second phase delay progression, where the first voltage value and the second voltage value have opposite signs. In a further embodiment, the first voltage value and the second voltage value have equal magnitudes. In certain embodiments, the voltage values having equal magnitudes includes the voltage values differing, within a noise voltage value, by a voltage difference corresponding to a π phase delay, and/or an nπ phase delay. An example nπ phase delay includes n having an integer value between 1 and 4, inclusive. An example system includes the voltage values having an opposite sign relative to a nominal voltage. An example system includes the first voltage value and the second voltage value symmetrically distributed about a 0π phase shift. An example low-side electrode layer includes a number of discrete electrodes. An example low-side electrode layer includes a continuous electrode. An example low-side electrode layer includes a reflective layer - for example formed using a reflective electrode, and/or using a reflective layer coupled to the low-side electrode layer. An example apparatus, which includes a thin beam steering device coupled with a fishtail booster, is capable to steer an incident EM beam to a range of at least +/- 20 degrees in a given axis, and/or to a range of at least +/- 30 degrees in a given axis. In certain embodiments, the convex lens portion and the concave lens portion are formed from separate substrates, and/or are formed utilizing manufacturing techniques having similar tolerance values. In certain embodiments, the convex lens portion and the concave lens portion are formed from a shared substrate.

An example system includes a polarization birefringence grating (PBG) positioned between an electromagnetic (EM) source and a first volume hologram, the first volume hologram positioned between the PBG and a second volume hologram, and the second volume hologram interposed between the first volume hologram and a continuous steering element. An example system includes the continuous steering element provided as an alternating resistor embodiment, for example as set forth in the example system and apparatus preceding, or as otherwise set forth throughout the present disclosure. An example PBG is responsive to a polarization of an incident beam from the EM source to selectively steer the incident beam to a first selected angle or a second selected angle, where the first volume hologram is responsive to the first selected angle, and where the second volume hologram is responsive to the second selected angle. Each volume hologram increases a steered angle of the incident EM beam in response to each respective selected angle. In certain embodiments, the PBG is replaced with a discrete or continuous steering element. In certain embodiments, the PBG and one or both volume holograms are replaced with one or more discrete or continuous steering elements.

Certain further aspects of the example system are set forth following, any one or more of which may be present in certain embodiments. An example system includes a controller having a steering request circuit that interprets a steering request value, a steering configuration circuit that determines a number of EO command values in response to the steering request value, and where the number of EO command values correspond to a half-wave voltage profile. The example controller further includes a steering implementation circuit that provides a number of voltage commands in response to the number of EO command values. An example system includes the electrodes of the high-side electrode layer responsive to the number of voltage commands. An example steering configuration circuit further determines a polarization orientation in response to the steering request value, and a selectively polarized EM source provides the incident beam to the PBG (and/or first steering layer) at a selected first polarization corresponding to the first selected angle, or a selected second polarization corresponding to the second selected angle. An example selectively polarized EM source is responsive to the polarization orientation.

An example half-wave voltage profile includes a first voltage value for a last electrode of a first phase delay progression, and a second voltage value for a first electrode of a second phase delay progression, where the first voltage value and the second voltage value have opposite signs. In a further embodiment, the first voltage value and the second voltage value have equal magnitudes. In certain embodiments, the voltage values having equal magnitudes includes the voltage values differing, within a noise voltage value, by a voltage difference corresponding to a π phase delay, and/or an nπ phase delay. An example nπ phase delay includes n having an integer value between 1 and 4, inclusive. An example system includes the voltage values having an opposite sign relative to a nominal voltage. An example system includes the first voltage value and the second voltage value symmetrically distributed about a 0π phase shift. An example low-side electrode layer includes a number of discrete electrodes. An example low-side electrode layer includes a continuous electrode. An example low-side electrode layer includes a reflective layer - for example formed using a reflective electrode, and/or using a reflective layer coupled to the low-side electrode layer. An example system includes a fishtail booster associated with the continuous steering element, as a second steering layer of the beam steering system. An example second steering layer of the beam steering system is capable to provide a combined steering capability (e.g., the continuous steering element and fishtail booster together) of greater than +/- 25 degrees. An example beam steering system, for example including the first steering layer (e.g., PBG and volume holograms, or other steering arrangements) and the second steering layer (e.g., continuous steering element and fishtail booster), includes a final steering capability of greater than +/- 30 degrees, greater than +/- 45 degrees, between +/-45 degrees to +/-60 degrees, and/or greater than +/- 60 degrees.

An example optical steering apparatus includes a first steering later that adjusts an incident angle of an EM beam on a second steering layer, where the first steering layer is positioned between an EM source and the second steering layer. An example second steering layer is provided as an alternating resistor embodiment of a thin beam scanning device, for example as set forth in the examples preceding, or as otherwise set forth throughout the present disclosure.

Certain further aspects of the example optical steering apparatus are described following, any one or more of which may be present in certain embodiments. An example first steering layer includes a discrete steering element that selectively steers the incident EM beam and a selected first angle or second angle. An example first steering layer further includes a first volume hologram responsive to the selected first angle to increase the selected first angle to an increased first angle, and a second volume hologram responsive to the selected second angle to increase the selected second angle to an increased second angle. An example first steering layer includes PBG providing the selected first angle or second angle, for example responsive to a polarization of the incident EM beam. An example optical steering apparatus further includes a selectively polarized EM source that provides the incident EM beam to the first steering layer at a selected polarization to select the first angle or the second angle.

An example optical steering apparatus includes the first steering layer having a thin beam steering device. The example thin beam steering device is capable to provide the incident EM beam at a selected angle - for example to activate either the first volume hologram or the second volume hologram, and/or to bypass the volume holograms and provide a selected angle incident on the second steering layer. In certain embodiments, the first steering layer includes the thin beam steering device, with no volume holograms present, and/or with no volume holograms for a given steering axis. An example optical steering apparatus includes a thin beam steering device, included in the first steering layer and/or the second steering layer, operating a half-wave voltage profile. An example optical steering apparatus includes a thin beam steering device of the second steering layer having an associated fishtail booster. An example thin beam steering device includes a thin beam steering device having an arrangement such as: castle arrangement device; a castle pro arrangement device; a chess arrangement device; a chess pro arrangement device; and/or an alternating resistor arrangement device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a graph depicting modulo 2π phase shifting to create beam steering.

FIG. 2 shows a graph depicting the effect of fringing fields on phase profile associated for a previously known electro optical thin film scanner.

FIG. 3 is a plan view of a previously known bulk beam steering system.

FIG. 4 is a plan view of a previously known 2-dimensional bulk beam steering system.

FIG. 5 is a plan view of a single layer of active EO material and insulator material to reduce fringing field effects.

FIG. 6 is a graph depicting step increments of two phase delay progressions with a reset therebetween, using conductive electrodes.

FIG. 7 is a plan view of an embodiment having tilted electrodes and insulators to reduce fringing field effects.

FIG. 8 is a graph depicting step increments of two phase delay progressions with a reset therebetween, using resistive or tilted electrodes.

FIG. 9 is a plan view of a single layer of active EO material and insulator material, having a reflective layer.

FIG. 10 is a plan view an embodiment having tilted electrodes and insulators, having a reflective layer.

FIG. 11 is a schematic depiction of an EO active layer having a number of active cells with discrete low-side electrodes.

FIG. 12 depicts an embodiment for a two-layer embodiment having a common or continuous low-side electrode.

FIG. 13 depicts an embodiment for a four-layer embodiment having common or continuous low-side electrodes.

FIG. 14 depicts an embodiment for a two-layer embodiment having a shared common or continuous low-side electrode.

FIG. 15 depicts an embodiment for a four-layer embodiment having shared common or continuous low-side electrodes.

FIG. 16 depicts a two-layer embodiment having a common or continuous low-side electrode.

FIG. 17 depicts a two-layer embodiment having a shared common or continuous low-side electrode.

FIG. 18 depicts a single layer of active EO material having active cells with varying thicknesses and a common or continuous low-side electrode.

FIG. 19 is a schematic diagram of a controller for steering an incident EM beam.

FIG. 20 is a schematic diagram of another embodiment of a controller for providing EM beam steering commands.

FIG. 21 is a schematic flow diagram of a procedure for steering incident EM beams having distinct wavelength values.

FIG. 22 is a schematic flow diagram of a procedure for steering an incident EM beam in more than one axis or polarity.

FIG. 23 is a schematic flow diagram of a procedure for steering an incident EM beam.

FIG. 24 is a schematic flow diagram of a procedure for making and using an EM beam steering device.

FIG. 25 is a schematic flow diagram of a procedure for operating an EM beam steering device.

FIG. 26 is a schematic diagram of a beam steering device.

FIG. 27 depicts an embodiment of a single active layer of a beam steering device.

FIG. 28 depicts another embodiment of a single active layer of a beam steering device.

FIG. 29 is a schematic diagram of a controller for steering an incident EM beam.

FIG. 30 is a graph depicting an example phase profile using a half-wave voltage profile.

FIG. 31 is a schematic flow diagram of a procedure for operating an EM beam steering device.

FIG. 32 is a schematic diagram of a beam steering device utilizing a zero power meniscus lens.

FIG. 33 is a schematic diagram of a beam steering device utilizing a zero power meniscus lens.

FIG. 34 is a schematic depiction of a system for steering an EM beam.

FIGS. 35-37 are illustrative depictions for steering capability of a continuous steering element.

FIG. 38 is a schematic depiction of a thin beam steering device associated with a fishtail booster.

FIG. 39 is a schematic depiction of a system for steering an EM beam.

FIG. 40 is an illustrative depiction for steering capability of a continuous steering element associated with a fishtail booster.

FIG. 41 depicts illustrative data for reflective losses at high steering angles.

FIG. 42 is a schematic block diagram of a controller for steering an EM beam.

FIG. 43 is a schematic flow diagram of a procedure for steering an EM beam.

FIG. 44 is a schematic flow diagram of a procedure for steering an EM beam.

FIG. 45 depicts an embodiment of a single active layer of a beam steering device.

FIG. 46 is a graph depicting step increments of a number of phase delay progressions with a reset therebetween, using alternating resistor-electrode elements.

FIG. 47 is an illustrative depiction for steering capability of a steering system according to the present disclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles disclosed herein as would normally occur to one skilled in the art to which this disclosure pertains.

This disclosure relates to the field of optical beam steering and in certain embodiments includes modulo 2πn and bulk active layer beam steering approaches, with a reduced number of moving parts, and/or no moving parts. More particularly, this disclosure teaches a unique, new, diffraction-based beam steering device made of electro optical crystals, liquid crystals, quantum dot materials, or any other material whose index of refraction can be dynamically changed. Example devices will have no moving parts. In certain embodiments, molecules in the electro-active material move, such as in a nematic liquid crystal.

Steering an optical beam without moving parts requires the ability to change the phase front exiting an optical device compared to the phase front entering a device. The direction a beam is travelling can be perpendicular to the phase front of the beam. Traditionally, the phase front of an optical beam, and the direction the beam is travelling, is changed by moving a mirror, or a transparent optical element with an index of refraction different from air. Two fundamental non-mechanical methods of creating a phase difference across an optical beam resulting in a steered optical beam are described herein. One method is to create an optical path delay (“OPD”), which is equivalent to a phase delay for a certain wavelength, and the other is to directly create a phase delay. An example disclosure of the direct phase approach is set forth in the paper by S. Pancharatnam, in Proceedings of the Indian Academy of Sciences, vol XLI, no. 4, sec. A, 137, 1955. Some of the background for this disclosure is discussed in “A review of phased array steering for narrow-band electro-optical systems”, by Paul F McManamon, Philip J Bos, Michael J Escuti, Jason Heikenfeld, Steve Serati, Huikai Xie, Edward A Watson. The Pancharatnam paper, which may be referred to as “Reference 1” hereinafter, discusses these technologies, and is incorporated herein by reference in its entirety for all purposes.

Another example method to steer light without mechanical motion includes writing a prism. Certain challenges with this approach include the difficulty in creating an OPD as large as would be required to write a full prism of appreciable width. For example, a 10-cm wide aperture steering to 30 degrees would require > 5 cm OPD on the thick side of the prism. However, for a narrow wavelength, it is advantageous that light is a sine wave.

With a sine wave it does not matter if there is a 0, 2π, 4π or 2nπ phase shift. The unfolded phase profile is the same. Therefore, as one moves across the width of the prism, an OPD can be created that subtracts 2π of phase, or one wavelength, every time the phase reaches 2π, resulting in a sawtooth OPD and a sawtooth phase profile. When the phase profile is unfolded, it is the same for the design wavelength as the profile resulting from light travelling through a prism. Unfolding the phase front means adding the phase, or OPD, resets back into the prism. Resets of any multiple of 2π, or any multiple of one wavelength, can be used. If resets are created perfectly, the unfolded phase at the design wavelength looks like the phase profile that would result from propagation through a prism and steers light in the same manner as a phase shift resulting from light travelling through a prism.

A modulo 2π phase profile should be interpreted to mean a 2πn phase profile, with resets of any multiple of one wavelength of OPD. Discrete increment modulo 2π beam steering is shown in FIG. 1 . In the example shown in FIG. 1 , discrete steps are used to build up to one wavelength (or a multiple of wavelengths, 2πn), or 2π phase shift. For example, discrete steps of 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, and 330 degrees can be used, and then reset (e.g. at position 108) back to 0 degrees instead of going to 360 degrees, because 0 degrees and 360 degrees are the same in a sine wave. This is what would result from individual electrodes imposing an index change on a material, ignoring any fringing field effects. The benefit of using a modulo 2π phase profile is that the required OPD can be small, on the order of a single wavelength (or a small multiple of the wavelength). In the example of FIG. 1 , a number of phase delay progression stages (e.g., group 102) are utilized to build up the 2πn phase shift, and a reset 108 is performed between each phase delay progression stage 102. The unfolded phase profile 104 is depicted, which is the equivalent phase shift of an incoming undisturbed phase front 106 (defined by the EM beam, and co-located with the position axis). It will be understood that any number of phase delay progression stages 102 may be utilized, each having any number of discrete steps to build them. Additionally, phase delay progression stages 102 may not be discrete, but may be continuous or partially continuous as described throughout the present disclosure. Additionally, each phase delay progression stage 102 may be distinct from one or more of the other phase delay progression stages 102, for example where a first stage 102 provides a 2π phase shift, and where a second stage 102 provides a 4π phase shift (e.g., utilizing twice the distance along the position axis, thereby providing the designed unfolded phase profile 104). Additionally or alternatively, phase delay progression stages 102 need not be in the same plane - for example where the incident EM beam encounters one of the phase delay progression stages 102 on a first plane, and a second one of the phase delay progression stages 102 on a second plane (e.g., reference FIG. 12 ).

For Modulo 2πn beam steering the maximum required OPD (i.e., the minimum thickness of the electro-optic (EO) material at the maximum phase shift location) is approximately equal to the wavelength of the light being steered. In certain embodiments, a thicker EO material may be utilized, such as a multiple of the wavelength of light being steered. The modulo 2π steering approach makes the beam steerer subject to wavelength dependence, or dispersion. The wavelength dependence results in varying wavelengths steered to varying angles. This wavelength dependence is discussed in: P. F. McManamon, E. A. Watson, T. A. Dorschner, L. J. Barnes, “Nonmechanical beam steering for active and passive sensors,” SPIE 1417, 110, 1991, p 194. The McManamon paper “Nonmechanical beam steering...”, which may be referred to as “Reference 2” hereinafter, is incorporated herein by reference in its entirety for all purposes. The wavelength dependence is further discussed in: P.F. McManamon, J. Shi, and P. Bos, “Broadband optical phased-array beam steering,” Opt. Eng. 44, 128004, 2005. The McManamon paper “Broadband optical phased-array beam steering”, which may be referred to as “Reference 3” hereinafter, is incorporated herein by reference in its entirety for all purposes.

Wherever a wavelength is recited (e.g., of light, EM radiation, and/or an optical or photonic beam) and/or where λ is recited, throughout the present disclosure, it will be understood that the wavelength (or λ) may be a nominal wavelength, a particular wavelength, and/or an effective wavelength. For example, a nominal wavelength may be the wavelength of a target or considered EM radiation frequency in a vacuum, in air, or under selected conditions. In another example, a particular wavelength may be a wavelength of a target or considered EM radiation frequency at specific conditions, such as through an EO active material at a selected voltage value (e.g., thereby at a selected refractive index for that frequency of EM radiation). In another example, an effective wavelength may be the in-situ wavelength of the EM radiation frequency in the EO active material, an average of certain values (e.g., an average of the high- and low- phase delayed values in a given active cell, etc.), and/or one or more active cells may be configured for distinct λ values, even for a particular frequency of EM radiation (e.g., depending upon the current, expected, or designed optical conditions for the one or more active cells). Accordingly, λ should be understood throughout the present disclosure to indicate any of these usages. One of skill in the art, having the benefit of the present disclosure and information ordinarily available when contemplating a particular system and/or an aspect of the system, can readily determine which usage of A is relevant for the particular system and/or the aspect of the system. Certain considerations for determining which one or more usage of λ applies to a particular system or aspect of the system include, without limitation: the optical characteristics of the EO active material(s) of the system; the phase delay progression planned for the system; the voltage profile and/or optical characteristic profile of the system; the efficiency considerations for the system including the cost of power, the risks related to side lobes, and/or the costs associated with undesired thermal generation in relevant parts of the system; the duty cycle of operating conditions (e.g., power throughput, steering directions and magnitudes, and/or on-time); and/or the steering capability (e.g., degree of steering, number of axes of steering, and/or number of polarities of steering) to be supported by the system.

An important parameter for beam steering is steering efficiency. As used herein, the term steering efficiency should be understood broadly. Various options and configurations described throughout the present disclosure affect different aspects of the steering efficiency, and accordingly it will be understood by one of skill in the art, having the benefit of the present disclosure, how to determine which aspects of the present disclosure are important to varying embodiments. Without limitation, steering efficiency can be understood to include energy transport considerations, cost considerations, risk considerations, and/or capability considerations. Without limitation, steering efficiency can be understood to be any one or more of the following: the amount of incident energy of the EM on the beam steering device that reaches the targeted location; the similarity of the phase profile of the steered EM beam on reach the target relative to the incident EM beam and/or relative to an idealized prism; the amount of energy of the incident EM beam that does not reach the target location (e.g., side lobes and/or heating losses); the amount of energy of the incident EM beam that creates an undesirable effect (e.g., a concentrated side lobe); the amount of energy of the incident EM beam that dissipates as heat and/or where the heat is dissipated; the number of electro-optical (EO) layers utilized to achieve a given steering capability; the cost of manufacture (e.g., materials, fabrication, testing, etc.) for a particular design; the opportunity cost of a lower system capability (e.g., steering amount, wavelengths supported, profile consistency, etc.); the capital and/or operating cost of a higher system capability; and/or the risk cost of a particular steering device (e.g., due to side lobes and/or the particular arrangements of the side lobes, wavelength selections which may have varying risks, and/or system reliability or power consumption which may put certain applications at risk).

Certain considerations to determine which steering efficiency factors are important for a particular application include, without limitation: the utilization environment for the beam steering device including robustness to side lobes; EM wavelength values to be utilized; capital cost sensitivity; operating cost sensitivity; costs and availability of power for the beam steering device in use; costs and availability of computing power for the beam steering device in use; costs, availability, and capability for manufacturing including materials and fabrication; the critical mission aspects for a particular application such as targeting capability, response time, and similarity of phase profile requirements; and/or the sensitivity of parts of the beam steering device and/or the utilization environment to heating and/or side lobe energy from beam steering operations. One of skill in the art, having the benefit of the disclosure herein and information ordinarily available when contemplating a particular system, can readily determine which factors of steering efficiency determinations are important to a particular embodiment, and further which features of systems and/or techniques described throughout the present disclosure relate to those factors of steering efficiency. The foregoing sets forth an example of certain considerations for certain systems, and any other considerations set forth throughout the present disclosure may also be utilized in configuring a particular embodiment of the present disclosure.

The terms optical light, optical, EM radiation, EM beam, light, photonic beam, and other similar terms as used throughout the present disclosure should be understood broadly. The present disclosure contemplates steering EM radiation of any type depending upon the application and the available materials. In certain embodiments, EM radiation as utilized herein contemplates optical light, or light that is within the visible spectrum. In certain embodiments, optical light additionally includes at least a portion of the ultra-violet spectrum, and/or at least a portion of the infra-red spectrum. In certain embodiments, optical light and/or EM radiation includes one or more contemplated wavelengths and/or portions of the EM spectrum, and does not include portions of the EM spectrum that may otherwise be considered “optical light” outside the context of the particular system. It will be understood that various electro-magnetic wavelengths of interest are contemplated herein, including wavelengths that are not visible, and/or are not typically described as optical wavelengths or “light.” Without limitation, the terms optical and light, as used herein, include at least infrared, visible, and ultra-violet frequencies, and in certain embodiments may include frequencies of the electromagnetic spectrum that are outside these ranges. One of skill in the art, having the benefit of the present disclosure and information ordinarily available when contemplating a particular system, can readily determine the EM radiation, optical light, light, and/or EM beam parameters for the system. Certain considerations when determining the EM radiation, optical light, light, and/or EM beam parameters for a system include, without limitation: the available materials for fabricating EO layers, substrates, reflective materials, and/or electrodes; the transmissivity and/or optical change characteristics for materials at frequencies of interest; the EM frequency requirements for an application (e.g., eye safety, resolution requirements, and/or available EM sources); and/or the available thickness of materials as fabricated (e.g., limiting the steerable wavelengths of EM radiation such as at longer wavelengths).

One issue with any modulo 2π beam steering system that affects the steering efficiency is “fly-back,” which refers to the spatial distance required to reduce the OPD by a 2πn wavelength (e.g., a “reset”, such as from approximately a multiple of one wavelength, or 2πn phase shift, to near zero). Reducing the OPD from that which results in a 2πn phase shift to zero means from approximately 2πn to approximately zero. There are various embodiments and techniques for specifying the exact OPD level from which a reset subtracts OPD. While each of these techniques reduce the OPD by 2πn in phase for the design wavelength, they do not all start at exactly an OPD that is equivalent to a 2πn phase shift, but can start at somewhat higher or lower values that are close to 2πn, and can end at values that are somewhat higher or lower than zero. For example, referencing FIG. 2 , a phase shift curve 200 depicts an example reset portion 202. An ideal reset 202 would show the phase shift curve 200 dropping vertically from a phase shift profile that followed an ideal prism profile to a value shifted by 2πn to the selected reset state (which may be a non-zero voltage value), and the progressing again at an ideal prism angle in the next stage. However, previously known modulo 2π beam steering system have a significant fly-back effect as depicted in FIG. 2 , where the pre-reset profile falls off of the ideal prism profile before reaching the reset portion, and does not fall all the way to the designed reset value before returning to the prism curve. The fly-back effect causes a loss of steering efficiency, where a portion of the incident EM beam is not steered to the desired location, and further can cause heating, side lobes, or other undesired effects as the improperly steered energy of the EM beam is dissipated in another portion of the system or the environment.

Certain embodiments herein utilize a polarization birefringence grating (PBG). A PBG selectively steers an incident beam to a selected fixed angle left or right, where the direction is dependent upon the polarization of the incoming light. PBGs, as utilized herein, can reference either birefringement gratings (e.g., a sawtooth birefringement grating), but may also reference birefringement prisms. PBGs may be responsive to either circular/elliptical polarization or to linear polarization. PBGs adjust the steering angle by a fixed amount, and are generally capable of a few degrees of steering. PBGs steering to larger angles, without other elements as set forth herein, require multiple stages and therefore accumulating efficiency losses with each stage, and for prism based PBGs the thickness requirement for the birefringement prism may be large enough (e.g., 20° steering with a 0.2 birefringence index and a 5 cm aperture would be 8 cm thick), which can drive sizing, cost, and weight issues, in addition to walkoff complications (e.g., where the steered beam at least partially impinges on a side wall of the optical path, steering device, etc.). Additionally, utilization of steering using multiple stages of PBGs, and more than one steering direction (e.g., azimuthal and elevation) may result in additional stages for polarization management (e.g., half-wave plates, etc.), leading to additional efficiency losses. PBGs are capable to steer normal beams (e.g., the initial incident EM beam, and/or received EM radiation from a target observed location), and/or to additively steer to a beam that is already steered to some extent. Accordingly, as set forth throughout the present disclosure, PBGs have features that provide benefits for certain embodiments, and are included, for at least certain steering layers, in certain embodiments of the present disclosure. In certain embodiments, high capability and high efficiency beam steering devices of the present disclosure do not include a PBG.

Certain embodiments herein utilize a volume hologram. A volume hologram may be implemented in any material known in the art, but an example includes photo-thermal glass. The volume hologram is created with one or more reference beams, providing for steering of a signal beam (e.g., an incident beam from an EM source and/or received EM radiation from an observed location) at a discrete angle. The volume hologram is responsive to an incident EM beam at a specific angle (and/or at a number of specific angles), and steers the incident EM beam received at the specific angle to a discrete selected angle. Accordingly, a volume hologram provides for a convenient discrete steering step for the incident EM beam - for example receiving the incident EM beam at a first angle (e.g., 2 degrees off-center), and steering it to a second angle (e.g., 5 degrees of steering, or 7 degrees off-center, in the example). The volume hologram does not provide steering action for incident EM radiation that is not at one of the selected angles, for example a normal (perpendicular) incident EM beam. Accordingly, a volume hologram supports embodiments where a beam incident to the volume hologram is controllably at the selected angle(s), or not, and where a discrete steering angle applied is desired at the volume hologram stage. Volume holograms are generally efficient, over 99% efficient with a single hologram written into a single piece of glass, and still about 98% efficient with two holograms written into the single piece of glass. Volume holograms are capable to sustain high power throughput. However, the limitations of volume holograms, including only diffracting light of the proper wavelength and incidence angle, as well as emitting light at a fixed steering angle, introduce complications that can lead to increased losses, cost, and the like. For example, steering to high angles in a number of stages, steering in two axes (e.g., elevation and azimuth), and steering in multiple directions (e.g., 40° each right and left) can lead to a large number of volume hologram stages to provide sufficient steering capabilities for an application. Each stage is efficient for diffraction considerations, but introduces scattering, reflection, and absorption losses, and many stages together can lead to significant losses. Additionally, with multiple stages of a volume hologram, walkoff considerations may limit some applications, and/or lead to an increase in size, weight, etc. for a beam steering device. Additionally, the requirement of a volume hologram for a specific incident light angle, and the discrete steering nature of the volume hologram, can lead to added expense to manage these capabilities, such as the use of a continuous steering device before the volume hologram (e.g., to provide a selected incident angle for the volume hologram) and after the volume hologram (e.g., to provide steering to a desired location). Accordingly, as set forth throughout the present disclosure, volume holograms have features that provide benefits for certain embodiments, and are included, for at least certain steering layers, in certain embodiments of the present disclosure. In certain embodiments, high capability and high efficiency beam steering devices of the present disclosure do not include a volume hologram.

Embodiments herein reference steering of an incident EM beam, for clarity of the present disclosure. Embodiments described throughout the present disclosure additionally contemplate steering of an optical guide path (e.g., a “beam steering device,” “optical steering device,” “optical steering apparatus”, and/or other terms) from an observed region (e.g., a target area, object, scanned area, etc.) to a target location (e.g., a photonic array, sensor, camera, and/or other optical observation device). Embodiments steering an EM beam provided by an EM source for clarity and convenience of the description.

Embodiments herein reference “thin” beam steering devices. Certain examples further include a modulo 2πn steering device, a device having a chess arrangement, a device having a castle arrangement, a device having a chess pro arrangement, a device having a castle pro arrangement, and/or a device utilizing a half-wave voltage profile. Without limitation to any other aspect of the present disclosure, any descriptions of these terms as set forth in US PCT application PCT/US2019/023915 are contemplated herein (which is incorporated by reference herein, and to which the present disclosure claims priority). Embodiments herein may be referenced as a thin beam steering device, thin beam steering scanner, and/or other similar terminology.

Embodiments herein reference “bulk” steering devices, including bulk steering devices having a convex emission face. Without limitation to any other aspect of the present disclosure, any descriptions of these terms as set forth in US PCT application PCT/US19/57616 are contemplated herein (which is incorporated by reference herein, and to which the present disclosure claims priority), including at least as represented in Figs. 33-53, 59-61, 64, 66-69, and 74, and the related descriptions.

Without limitation to any other aspect of the present disclosure, an example thin beam steering device includes an alternating resistor-electrode embodiment, for example utilizing alternating resistors and electrodes on the electrode high side layer. The alternating resistor-electrode embodiment provides for a linearized phase delay progression across the width (e.g., perpendicular to the incident EM beam) of the beam steering device, improving the steering efficiency, the faithful reconstruction of the wave front after steering operations, and reducing losses of the steered energy to undesirable locations (e.g., beam energy steered somewhere that is not intended, and/or impingement on a sidewall or component of the steering device that may cause heating or other undesired interactions).

Embodiments herein reference a “fishtail booster”, “meniscus lens”, and/or similar terms. Without limitation to any other aspect of the present disclosure, any descriptions as set forth in US PCT application PCT/US19/57616 are contemplated herein, including at least as represented in Figs. 62-63 and the related descriptions.

The example of FIG. 1 depicts an idealized modulo 2πn system having no fly-back effect, while the example of FIG. 2 depicts an example previously known modulo 2πn system having a nominal fly-back effect. Various features throughout the present disclosure have been found to greatly reduce the fly-back effect, including without limitation the utilization of insulators, vertical spatial changes between adjacent phase delay progression stages (e.g., reference FIG. 12 and FIG. 18 ), enhanced insulation at reset positions, and/or control or modulation of electrodes. In certain embodiments, systems and/or methods for performing modulo 2πn beam steering described throughout the present disclosure can approximate the unfolded phase profile 104 depicted in FIG. 1 .

FIG. 6 is an example depiction of a realistic phase profile 602 which, according to modeling and calculations, it is believed to be achievable using various aspects of the present disclosure. The example of FIG. 6 utilizes conductive electrodes. The representation of FIG. 6 is non-limiting: certain systems may have a less ideal phase profile 602 than that depicted in FIG. 6 and nevertheless realize certain benefits of the present disclosure, and certain systems may have a more ideal phase profile 602 than that depicted in FIG. 6 , such as by combining aspects of the present disclosure, utilizing higher capability materials, more elaborate configurations of electrodes, controllable electrodes, tilted or contoured electrodes, and/or by increasing the number of steps in one or more of the phase delay progressions.

FIG. 8 is an example depiction of a realistic phase profile 802 which, according to modeling and calculations, it is believed to be achievable using various aspects of the present disclosure. The example of FIG. 8 utilizes resistive electrodes. The representation of FIG. 8 is non-limiting: certain systems may have a less ideal phase profile 802 than that depicted in FIG. 8 and nevertheless realize certain benefits of the present disclosure, and certain systems may have a more ideal phase profile 802 than that depicted in FIG. 8 , such as by combining aspects of the present disclosure, utilizing higher capability materials, more elaborate configurations of electrodes, controllable electrodes, tilted or contoured electrodes, and/or by increasing the number of steps in one or more of the phase delay progressions.

Disclosed herein are example modulo 2πn active material steering approaches, where a modulo 2πn active material will be from sub-micron level thickness to many tens, or even hundreds, of microns thick. Certain example modulo 2πn active material beam steering approaches taught use resets to limit the thickness of the active layer. An example embodiment utilizes an active single layer with thin insulators between electrodes going through the active material. Certain features described herein enhance efficiency throughput, such as, use of an insulator, an optically active material, and/or a substrate transparent to the incoming light and/or having respective refractive indexes in a configured manner, such as refractive indexes that are similar. The insulators between the electrodes may, or may not, be all the way through the active layer. In certain embodiments, insulators may not be transparent to the incoming light.

The term transparent, as used herein, should be understood broadly, and includes at least materials that allow transmission of electromagnetic radiation of selected wavelengths: to a selected degree, virtually completely, above a threshold level, and/or sufficiently to perform the underlying task. The amount of transmission that is transparent, for example sufficient to perform the underlying task, will be understood to one of skill in the art having the benefit of the present disclosure. Without limitation, certain considerations to determine an amount of transmission that is transparent include: the cost and availability of manufacturing materials; the cost of fabricating a given device; the utilization of the device including required resolutions, detection thresholds, and the like; the criticality of the device relative to a system or application of the device; heat dissipation constraints and/or considerations of the device; and/or the availability of processing resources to enhance the capability of the device in the presence of reduced transmission of EM radiation through the transparent components of the device. A transmission level that is transparent for one embodiment in the full context of a particular device or system may be considered not transparent in the full context of another device or system - for example a same insulator component that is transparent for one device may be reflective or not transparent in the context of another device.

In certain embodiments, materials are described throughout the present disclosure as having a close optical value or characteristic (and/or a similar optical value or characteristic), such as birefringence and/or an index of refraction. Optical values that are close depend upon the specific system. In certain embodiments, optical values that provide for sufficient transmission of light therethrough, and that do not disturb the EM beam such that a target steering capability and/or steering efficiency can be met are within the scope of close optical values as understood herein. In certain embodiments, EO active materials have varying optical characteristics, while insulators, substrate, and/or electrode materials have non-varying (or not intentionally varied) optical characteristics, and thereby a static optical characteristic is being matched (“close”) with a varying optical characteristic. In certain embodiments, the static optical value is selected to be a value between the ranges of the varied optical characteristic. In certain embodiments, the static optical value is selected to be a value near a more important portion of the varying optical characteristic range, for example close to the unsteered value, close to a maximum steering value, and/or close to a frequently occurring steering value. In certain embodiments, a static optical value may be outside of the range of the varied optical characteristic and nevertheless be close to the varied optical characteristic as contemplated herein. In certain embodiments, materials may be considered to have close or similar optical characteristics at EM frequencies of interest, even if they do not have close or similar optical characteristics away from EM frequencies of interest. In certain embodiments, as described throughout the present disclosure, anti-reflective materials may be utilized in addition to, or as a replacement for, the utilization of materials having closely matched optical characteristics. Example and non-limiting ranges for materials having a close optical characteristic include: materials which are the same (e.g., although one may have variance applied as an EO material), and/or materials which have a selected optical property at a selected wavelength or range of wavelengths (e.g., index of refraction at 9.4 µm) within a specified range (e.g., sufficient to support steering efficiency targets) at a specified condition (e.g., during selected steering operations). One of skill in the art, having the benefit of the present disclosure and information ordinarily available when contemplating a particular system, can readily determine materials having a close optical characteristic for the system. Certain considerations for determining whether materials have a close optical characteristic include, without limitation: the cost and availability of suitable materials (including material cost and/or fabrication considerations); the frequency(ies) of interest of steered EM beams; the target steering efficiency values; the target steering capability; the duty cycle of steering for the application (e.g., the range of steering values expected, and/or the time or power throughput at each steering value); and/or the availability of mitigating techniques for the system to compensate for optical differences (e.g., electrode configurations to recover steering efficiency, number of layers of active elements, the thickness of active and inactive elements, and/or utilization of “chess”, “castle”, or other configurations).

One design consideration is the thinness of the insulators between the active material. Thicker insulators generally provide for improved isolation between phase delay progression stages, and reduce fly-back at the reset position. Thinner insulators generally provide for enhanced active fill. Depending upon the materials for the active material, the insulator, and the substrate, either thinner or thicker insulators may increase the overall cost of the beam steering device, including effects on material costs and/or fabrication costs.

In certain embodiments, the ground (or low-side) electrode may be continuous (e.g., reference FIGS. 9, 10, or 12 ), and can be either reflective, or transparent to the incoming light. In certain embodiments, the electrically hot electrodes (or high-side) are discrete. In certain embodiments, the electrically hot electrodes are transparent to the incoming light. Alternately or additionally, one or more discrete electrodes could be embedded with, or behind, a reflective layer. In certain embodiments, the discrete electrodes are conductive.

An example second embodiment includes discrete electrodes that are resistive. Certain embodiments reduce the fringing field effect. An embodiment which has conductive electrodes, at least without further adjustments as described herein, will in general suffer from the quantization loss. In certain embodiments, the utilization of tilted and/or profiled electrodes can reduce or eliminate quantization losses, with or without the use of resistive electrodes. In certain embodiments, resistive electrodes can reduce or eliminate quantization losses. In certain embodiments, combinations of tilted and/or profiled electrodes with conductive and/or resistive electrodes may be utilized to support reduction or elimination of quantization losses, other system losses such as electrical losses, and/or to support various fabrication techniques. In an example embodiment having resistive electrodes, two voltages are applied to the resistive electrode, resulting in a tilted (or progressive) electric field, and a tilted (or progressive) index change. Example embodiments having resistive electrodes reduce quantization loss, for example by achieving a phase delay progression stage 102 with fewer electrodes, or even with a single electrode. In certain embodiments, two or more voltages are applied at selected locations across the electrode (e.g., using solid state devices electrically coupled to various positions of an electrode). The use of multiple voltages can achieve a non-linear slope of the voltages, for example to achieve a linear OPD change across the EO material or to be responsive to a non-linear electrode resistivity profile.

Another example embodiment includes at least two optically active rows 630 interposed between two substrates 600, 605, as shown in FIG. 12 . The example of FIG. 12 utilizes two, or a multiple of two, layers, alternating a transparent insulator with a transparent active layer, providing a 100% fill factor (or arbitrarily close to 100%, if desired) of active electro-optic (EO) material capable of causing an OPD change in the radiation. The example of FIG. 12 or similar arrangements can be utilized to avoid the profile gaps in the unfolded phase profile such as depicted in FIGS. 6 or 8 , which contribute to steering efficiency losses (e.g., by having an increased active layer fill factor). The example of FIG. 13 depicts a multiple of two layers, although any number of layers may be utilized. It will be understood that where an incident EM beam has portions that intersect a different number of layers (e.g., an embodiment having an odd number of active layers with alternating cells, where a first portion intersects two active layers and a second portion intersects three active layers), the OPD in one or more layers may be manipulated (e.g., using varying voltages and/or electrode configurations) to ensure that all steered portions of the incident EM beam are steered to the same degree. An example of FIG. 12 may utilize conductive electrodes or resistive electrodes. The example of FIG. 12 has reduced loss due to fringing fields.

A further example embodiment includes resistive electrodes and two, or more, voltages on one side (and/or a voltage progression), to reduce, or eliminate the quantization loss. The further example embodiment includes an effective 100% fill factor, negligible fringing field loss, and negligible quantization loss. For example, referencing FIGS. 12 and 13 , the utilization of resistive electrodes can reduce or eliminate quantization losses in the active cells. The example of FIG. 13 shows 4 device layers, but in certain embodiments more device layers could be used.

The example of FIG. 7 shows tilted electrodes 50. Tilted electrodes 50 can have a similar effect as resistive electrodes by creating a voltage variance across the active cell. In certain embodiments, the tilted electrodes 50 may be more difficult to fabricate, and the amount of tilt of the tilted electrodes 50 may not be adjustable at run-time. However, in certain embodiments, constructing the tilted electrodes 50 may provide for a field variance that more reliably achieves a design variance than a resistive electrode embodiment, and/or that provides for improved operation as wear and aging affect the resistance profile of the electrodes. Additionally or alternatively, example embodiments include adjustments to the tilted electrodes 50, such as providing more than one tilted electrode 50 per active cell, where selection of an active one of the tilted electrodes 50 provides for run-time adjustment of the electric field. The tilted electrodes 50 are depicted as a linear tilt, but the progression of the electrode and the spacing between the high-side electrode and the low-side electrode may be any shape, for example to account for a non-linear EO active material response and/or a non-linear resistance in the electrodes. In certain embodiments, given active cells may include tilted electrodes 50 and/or resistive electrodes. In certain embodiments, a first active cell may have a first tilted electrode 50 and/or resistive electrode configuration, and a second active cell may have a second tilted electrode 50 and/or resistive electrode configuration. In certain embodiments, the utilization of tilted electrodes 50 can produce a phase profile 802 similar to that depicted in FIG. 8 .

The example of FIG. 7 depicts the tilted electrode 50 progressing through the EO active material 10 at a selected trajectory. It will be understood that the tilted electrode 50 can be on a first side of the EO active material 10, for example with a shaped active cell rather than having the tilted electrode 50 traverse through the EO active material 10. The example of FIG. 7 depicts insulators 20 between active cells at a reset position, which may be configured as any insulator described throughout the present disclosure, including fully dividing active cells, partially dividing active cells, and/or the insulators 20 being a part of a substrate (not shown in FIG. 7 ). The example of FIG. 7 depicts a common ground electrode 40, although any ground electrode configuration described throughout the present disclosure may be utilized with tilted electrodes 50.

Yet another example embodiment includes at least two optically active rows separated by a continuous ground electrode, for example consistent with the depiction in FIG. 14 for two optically active rows, and in FIG. 15 for more than 2 optically active rows. Example embodiments include each active layer having an array of active cells. In the examples, an active cell is the EO active material positioned between the continuous ground electrode and a discrete electrode, and an insulator cell is positioned between each two active cells.

Referencing FIG. 11 , an EO active layer 3 is positioned between a row of discrete low-side electrodes 4 and a corresponding row of discrete high-side electrodes 2, and positioned within a substrate 1. The example of FIG. 11 utilizes the EO active material as an insulating gap between active cells and the substrate 1 as an insulating gap between high-side electrodes, where the active cells are the EO active layer 3 portions between the electrode pairs 4, 2. It can be seen that the embodiment of FIG. 11 , while not necessarily depicted to scale, may have a relatively low active fill factor, where a significant fraction of the incident EM beam does not pass through an active cell. In certain embodiments, the steering efficiency losses in an embodiment such as depicted in FIG. 11 are nevertheless acceptable. In certain embodiments, an embodiment such as depicted in FIG. 11 may additionally include another steering layer having an EO active material, high-side electrodes, and low-side electrodes (which may be shared with a different steering layer). The high-side electrodes 2 in FIG. 11 may be conductive or resistive. In certain embodiments, a configuration such as that depicted in FIG. 11 is not sufficiently capable to provide EM beam steering with acceptable steering efficiency for certain applications.

Referencing FIG. 12 , an example beam steering device includes a number of active cells 630, each positioned between a discrete high-side electrode 660 and a low-side electrode 650, 670. The low-side electrode 650, 670 in the example of FIG. 12 is a common ground electrode, with one common ground electrode 650, 670 for each active layer 610, 620. In the example of FIG. 12 , an upper substrate 600 and lower substrate 605 are provided, which may structurally define the beam steering device. In certain embodiments, one of the substrates 600, 605 may be reflective and/or include a reflective layer. In certain embodiments, ground electrode 670 may be reflective and/or include a reflective layer. The example beam steering device further includes a number of insulators 640, the insulators 640 positioned between each adjacent active cell 630. The insulators 640 may be a transparent material, and/or may have an optical characteristic that is close to the optical characteristic of the active cells 630. In certain embodiments, the insulators 640 may be air. In certain embodiments, the active cells 630 are arranged to apply a progressive phase delay to an incident EM beam, for example within a cell 630 (e.g., utilizing a resistive electrode or other aspect to apply a voltage gradient across the cell), and/or across several of the active cells 630, with the active cells 630 forming phase delay progression stages. It can be seen that a phase delay progression may begin with an active cell 630 in a first active layer 610, and continue with an active cell 630 in the second active layer 620. In the example of FIG. 12 , resets may occur at each active cell 630 (e.g., a next cell resets the phase delay by 2πn), or between adjacent cells 630 at the boundary several active cells 630 forming phase delay progression stages. In certain embodiments, both the geometry of the active cells 630 creating distance between the high-side electrodes 660, and the insulators 640 of the beam steering device, cooperate to provide for sharp resets that have greatly reduced fly-back effect and subsequent steering efficiency losses.

Referencing FIG. 13 , an example beam steering device is depicted having a number of active layers 680, 685, 690, 695. Each active layer 680, 685, 690, 695 includes active cells 740 including an EO active material positioned between a discrete high-side electrode 760 and a low-side electrode. The low-side electrodes 730 in the example of FIG. 13 are common ground electrodes, with one common ground electrode provided for each active layer 680, 685, 690, 695. The example beam steering device further includes substrates 710, 720, and insulators 750. The example beam steering device of FIG. 13 depicts multiple stacked active layers 680, 685, 690, 695, allowing for greater steering capability and/or greater steering efficiency of the device.

Referencing FIG. 14 , an example beam steering device is depicted having two active layers 770, 775. Each active layer 770, 775 includes active cells 790 including an EO active material positioned between a discrete high-side electrode 810 and a low-side electrode. The low-side electrode 1402 in the example of FIG. 14 is a common ground electrode, with two active layers 770, 775 sharing the common ground electrode. The example beam steering device includes a first substrate 805 on an incident side of the beam steering device, and a reflective layer 820 on the opposing side of the beam steering device. The use of a reflective layer 820 provides for additional steering capability, essentially doubling the effective steering capability of the active layers 770, 775.

Referencing FIG. 15 , an example beam steering device is depicted having four active layers 830, 840, 850, 860. Each active layer 830, 840, 850, 860 includes active cells 790 including an EO active material positioned between a discrete high-side electrode 810 and a low-side electrode. The low-side electrodes 1502, 1504 in the example of FIG. 15 are common ground electrodes, with two active layers (830, 840 and 850, 860, respectively) each sharing the common ground electrode. The example beam steering device includes a first substrate 870 on an incident side of the beam steering device, and a reflective layer 890 on a second substrate 875 on the opposing side of the beam steering device.

Yet another example embodiment includes at least two optically active rows (or active layers) separated by a continuous ground electrode, having resistive high-side electrodes and two, or more, voltages (and/or voltage gradients) provided across the active cells. Certain embodiments having at least two optically active rows separated by a continuous ground electrode have an effective 100% fill factor (e.g., the amount of the incident EM beam that is directed into active cells in at least one of the active layers), and/or an effective fill factor that is arbitrarily close to 100%, including greater than 90%, greater than 95%, greater than 97%, or greater than 99%. In certain embodiments, negligible fringing field loss and/or negligible quantization loss. In certain embodiments, there are even number of active rows, each active row including an array of active cells with an insulator cell located between each two active cells. Additionally or alternatively, an odd number of rows may be present in certain embodiments as will be understood by one of skill in the art having the benefit of the present disclosure. An example embodiment includes the positions of active cells and insulator cells in the neighboring rows that are opposite. In certain embodiments, the size and position of each active cell is selected in response to the size of the corresponding insulator cell in the next row - for example sized the same and aligned. In certain embodiments, active cells within a layer, and/or active cells in distinct layers, may be varied in size and/or thickness.

In certain embodiments, the active cells, thickness of active cells, electrodes, and applied voltages, are configured such that an incident EM beam of a selected wavelength (or frequency) experiences an identical or a sufficiently similar (e.g., consistent with the designed steering efficiency for the beam steering device) phase delay progression across the area of the EM beam such that the EM beam is steered to a desired degree at the selected steering efficiency. In certain embodiments, the active cells, thickness of active cells, electrodes, and applied voltages, are configured such that the steered portions of the EM beam (e.g., not the portions lost to an effective fill factor less than 100%) experience the identical or the sufficiently similar (e.g., consistent with the designed steering efficiency for the beam steering device) phase delay progression across the area of the EM beam. In certain embodiments, the active cells, thickness of active cells, electrodes, and applied voltages, are configured such that an incident EM beam of one of a number of selected wavelengths (or frequencies), and/or steered portions of such incident EM beams, experience an identical or a sufficiently similar (e.g., consistent with the designed steering efficiency for the beam steering device) phase delay progression at each of the selected frequencies. For example, and without limitation, an example beam steering device includes one or more active layers configured to steer a first selected frequency and to be transparent (or sufficiently transparent) to other selected frequencies, and further includes one or more other active layers configured to steer a second selected frequency and to be transparent (or sufficiently transparent) to the first selected frequency. In certain embodiments, an active layer can be configured to steer more than one frequency - for example where the steered frequencies are multiples of a same wavelength, such as when a thickness of an active cell is the same as a higher wavelength, and double (for example) the thickness of a lower wavelength.

In certain embodiments throughout the present disclosure, active cells in adjacent layers are offset (e.g., reference FIGS. 12-15 ) from each other in an alternating pattern. For the purpose of the present disclosure, such arrangements may be referenced as a Chess Scanner or a Chess Pattern. Certain embodiments having resistive discrete high-side electrodes and a Chess Pattern arrangement may be referenced as a Chess Scanner Pro (or a Chess Pattern Pro). The embodiments of FIGS. 12 to 15 depict two active layers cooperating to provide the effective fill area of the beam steering device in the Chess Pattern, but it will be understood that three or more layers, and/or randomized or pseudo-randomized layers can be arranged to provide the effective fill area of the beam steering device. The terminology of Chess Scanner or Chess Scanner Pro embodiments is used for convenience and clarity of the description herein. It will be understood that, in certain embodiments, the sizing, alignment, and/or arrangement of cells may vary such that the arrangement of the active cells and the insulator cells do not resemble a chess board. Without limitation, variance of sizing, alignment, and/or arrangement may include less than complete coverage of the optical area with cells, oblique, curved, or other non-perpendicular arrangements of cells, and/or cells having non-square shapes and/or varying shapes and sizes.

In certain embodiments, the substrates, active material, and/or insulators are transparent to the incoming optical wave to be deflected by the scanner, and/or have a similar refractive index between the two materials. It will be understood that transparency and/or refractive index similarity may improve the throughput of the device. In certain embodiments, materials may be non-transparent, transparent at selected wavelengths, and the like. An example embodiment includes an optional reflective layer added, which may be the last layer of the scanner (and/or the last optically active layer of the scanner). The reflective layer may be the last layer, and/or may be after a transparent last layer of the beam steering device. In certain embodiments, the continuous ground electrode in certain embodiments, and/or the last ground electrode in certain embodiments, may be reflective. The inclusion of a reflective layer causes the optical wave to traverse the scanner a second time, effectively doubling the thickness of the active layers, and increasing the steering capability and/or steering efficiency.

Each optically active row contains a series of cells made of an electro optically active material, such as an EO crystal (which could be KTN, PMN-PT, BaTIOs, SBN, or some other crystal material), a quantum dot material, a liquid crystal, and/or any other optically active material. In certain embodiments, distinct layers and/or distinct cells within a layer may include distinct materials from other layers or cell in a device. Each material whose index of refraction can be changed dynamically is sandwiched between two electrode layers. One layer can be ground, and one layer can apply a voltage other than ground. Alternately, both layers can apply a voltage different from zero. In certain embodiments it may be advantageous to use more than a single active material type.

Example electrodes are transparent to an incoming wave and can be either conductive, using only one applied voltage, or resistive using two or more applied voltages, while creating a linear, or non-linear, voltage ramp between the location where the two voltages are applied. The resistive layer will provide a varying voltage, from the lowest to the highest voltage applied to the electrode. In certain embodiments, portions of the high-side electrode may be resistive, and other portions of the high-side electrode may be conductive. In certain embodiments, the resistance of the high-side electrodes may be controllable - for example with multiple resistive elements provided across the high-side electrode, where a controller can configure the resistive arrangement during operations of the beam steering device. In a further example, solid state switches, Zener diodes, OP Amps, and/or other solid state devices may be used to provide suitable control of the high-side electrode resistances with a response time configured to meet the functions of the beam steering device.

In certain embodiments, the electrodes are fabricated from transparent conductor materials, such as In-Sn oxide or and In-Sn alloy. If a reflective layer is used on one side, then that side could be made with a conductor that is not transparent to optical radiation. The level of conductivity can be any of a wide variety of levels. A ground (or low-side) electrode can be continuous or discrete, but the high-side electrodes imposing spatially varying voltage are discrete and/or separated by insulator cells and/or geometric spacing providing an insulating function. In certain embodiments, insulator cells are made of the same material as the substrate, or some other material with a similar index of refraction as the substrate. As an alternative the insulator material could be air.

In certain embodiments, the refractive indices of the substrate, active material, and/or insulator have similar optical properties, and/or an anti-reflective coating can be used where material discontinuity occurs. The utilization of similar optical properties in materials can improve the throughput of the beam steering device. Using anti-reflection coatings can improve steering efficiency. In certain embodiments, an insulator cell is positioned between each of the optically active cells. In one embodiment, the arrangement of EO cells and insulators are reversed in each row. In certain embodiments, the active cells, whose index of refraction can be electronically modified, have the same size as the corresponding insulators in the next row. Alternately multiple active cells could be used, such that sum of the width of the cells is the same as the width of an insulator. In certain embodiments, the insulators, and substrate, are made of the same material, such SrTiO3 or infra-red glass to not only separate electrodes under different voltages but also to transmit the incoming EM wave. As an alternative one or more, or all, of the insulators may be air. In certain embodiments, the transparent insulator and active region above or below are the same size, and the next pair of insulator/active region materials are a distinct size.

For improved throughput the refractive indices of substrate, active and insulator cells should be close, and/or an anti-reflective coating can be used on any edges where material discontinuity occurs to improve steering efficiency. An ideal steering device would re-direct 100% of the impinging light. In one embodiment a high efficiency beam steering may redirect > 90% of the light impinging on a device to exit at the steered angle. Various beam steering applications can make use of different levels of steering efficiency. In one embodiment, the optical waves can be in the visible through long wave infrared. In one embodiment, the surface figure of the substrate, insulators and electrodes should be at least 1/50 of the wavelength of the incoming wave which in a UV, optical, or infrared, embodiment can be a wavelength of 0.25 to 12 microns. In certain embodiments, the optically active cells provide at least approximately one wavelength of phase delay, and thus have a depth or layer thickness of at least one wavelength divided by the index change ratio. In certain embodiments, a beam steering device having a reflective layer includes optically active cells providing at least approximately one-half wavelength of phase delay, and thus have a depth or layer thickness of at least one-half wavelength divided by the index change ratio. In certain embodiments, the thickness of the optically active cells progresses with the phase change delay, and/or may further include features to ensure that steering occurs in a single direction across the array of active cells (e.g., through mechanical control of the array facing, and/or control of the incident EM beam where such control is possible). The width of each active cell can be selected to adjust the deflection angle of the scanner, and further depends upon the phase delay progression scheme of a particular beam steering device.

In one embodiment, if the scanner is designed to steer a wave with 1.5-micron wavelength light to an angle of up to 30 degrees, the width of each EO cell (or active cell) would be 3 microns or less. If EO cells are of varying sizes then the largest cell will have a width of 3 microns. In the example, the size of insulator cells, which are between every two EO cells, are the same as the corresponding active cells in the next row.

An example includes the second optically active row of the scanner that is similar to the first row with the exception that the positions of the active, and insulator cells, are opposite. The alignment of electrodes and insulators in the two rows are very important to provide an optimum phase delay for the whole incoming wave. After an incoming optical or photonic wave traverses both layers the complete wave will have experienced a phase delay with discrete phase shifts based on the total shift of the two layers. Layer 1 will shift the optical or photonic wave in its active regions, then where layer 1 has an insulator, layer 2 will shift the wave in its active regions, and the shift will continue in this manner across the beam steering device.

Those active index changing layers that use a resistor, instead of a conductor, can vary the voltage across the active cell in a manner to match the waveform tilt resulting from the imposition of a series of discrete index change steps. In this manner, quantization loss, as explained in References 1 and 2, can be reduced or eliminated and approximately one wavelength of OPD can be provided in a single resistive electrode width, to deflect the incoming light to the maximum angle.

In one embodiment, each of the electrode layers can have thousands of discrete electrodes in one row, and each phase reset can contain one or more electrodes. Larger deflection angles require fewer electrodes of a certain width between resets, because the spatial period between resets is smaller. In the case of resistive electrodes, the reset period can be as small as one resistive electrode width. In case of having conductive electrodes, the reset period may, for one embodiment, include a discrete number of conductive electrodes for the largest angle, and more electrodes for a smaller angle. An eight-cell configuration would limit loss due to quantization to 5%, as explained in Reference 1. Depending upon the desired steering efficiency, certain embodiments may have as few as a three-cell configuration, although any number of cells may be provided including six, eight, ten, fifteen, or twenty cells before each reset period. As the modulation of the optical or photonic wave by the optically active cells is accumulative, an optional reflective layer can be added as the last layer of the scanner to provide either more deflection angle, or smaller cell thickness, by having the optical or photonic wave pass through the phase delay areas a second time.

An example embodiment includes the scanner made of at least two optically active layers interposed between two substrates. Each optically active row contains an array of cells whose index of refraction can be changed in one or both polarizations, such as liquid crystal, quantum dot, or EO crystals, such as SBN, PMN-PT, KTN, and/or BaTiOs. An example embodiment includes each active cell sandwiched between electrodes that are either conductive, or resistive. In the example embodiment, there is an insulator cell between every optically active cell in each row, and the arrangement of optically active cells and insulator cells is opposite in each row. In one embodiment the width of any corresponding cells in the different rows is exactly the same, so light undergoes an OPD associated with one active layer for each pair of active layer/insulator sections. The corresponding cells are aligned so one layer provides OPD, which for a given wavelength corresponds to a given phase shift, in one cell pair, and the second layer provides OPD, or phase shift, in the second cell pair.

In certain embodiments, the insulator cells, and substrates, are made of a material which has the same or a similar index of refraction, and is transparent (or sufficiently transparent) to the incoming optical wave. In one embodiment, all layers of the scanner are planarized to a surface flatness of one fiftieth (1/15) or better of the wavelength of the incident EM wave. The indices of refraction of the substrate, the active material, and the insulator cells should be similar, or it will be advantageous to apply an anti-reflecting coating on every discontinuity between materials to enhance the steering efficiency. A transmissive optical or photonic beam scanner can be made reflective if the last electrode is reflective, or a reflective layer is coated on one of the substrates. In certain embodiments, for example where accurate optical quality of the steered EM beam is not required for a particular application, the insulator cells, substrates, and/or active cells may have optical characteristics that are not similar, or that vary significantly.

In another embodiment of the present disclosure, the scanner can be made of two or any even number of optically active rows. In the example embodiment, each two optically active rows are interposed between two substrates, and/or a number of optically active rows are bounded by two substrate layers at opposing ends of the beam steering device. Each two rows are separated from each other by a common continuous transparent ground electrode. Each row comprises an array of optically active cells sandwiched between two electrodes that are either conductive or resistive, and an insulator cell is positioned between adjacent EO cells. In the example embodiments, the arrangement of EO cells and insulators are reverse in each row, and the size of the active cells in each row will be the same as the size of the corresponding insulator cells in the next row.

In certain embodiments, the insulator cells and substrates are made of a material with the same index of refraction and are transparent to the incoming optical or photonic wave like IR glass or SrTiO₃. The EO cells are made of any materials whose index of refraction can be electronically changed in one or both polarizations, like liquid crystal, quantum dot, or EO crystals like SBN, PMN-PT, KTN, BaTiOs. In certain embodiments, the layers of the scanner are planarized to a selected surface flatness to achieve the desired optical quality and/or steering efficiency. Example and non-limiting surface flatness values include a surface flatness of one-tenth, one-twentieth, one-fortieth, and/or one-fiftieth or better of the target wavelength. The indices of the substrate, active and insulator cells are close otherwise an anti-reflecting coating may be required on every edge where material discontinuity occurred. That agile transmissive optical or photonic wave scanner can be realized as reflective one if a reflective layer is coated on one of the substrates and/or on a common ground electrode.

One approach to determine the value from which OPD is subtracted (e.g., for a reset) is given in Gregor Thalhammer, Richard W. Bowman, Gordon D. Love, Miles J. Padgett, and Monika Ritsch-Marte, “Speeding up liquid crystal SLMs using overdrive with phase change reduction,” 28 Jan. 2013 / Vol. 21, No. 2 / OPTICS EXPRESS p 1779 -1797. The Thalhammer paper is incorporated herein by reference in the entirety for all purposes. Fine angular beam steering may also result in subtracting the reset from a value not exactly an increment of 2πn phase shift. The article by Burrell R. Hatcher, “Granularity of beam positions in digital phased arrays,” Proceedings of the IEEE (Volume: 56, Issue: 11, November 1968, teaches very fine angular steering using a phased array, but initiating the subtraction of a multiple of one wavelength of OPD from a value that is not an exact multiple of one wavelength of OPD, or 2πn of phase. The Hatcher paper, which may be referred to as “Reference 5” hereinafter, is incorporated herein by reference in the entirety for all purposes. The fly-back effect is a result of the inability of the device to change its voltage profile instantaneously between two sets of electrodes, which is shown in FIG. 2 . The fly-back region in FIG. 2 is the region for which the OPD or phase decreases as the distance increases.

Many modulo 2π steering embodiments, such as liquid crystals, or an electro-optical crystal, create an index change in one polarization as a result of applying an Electric, or E, field in the device as is shown in FIG. 11 . Other materials, such as quantum dots, can change the index in both polarizations when voltage is applied. An external electric field will be applied on the medium by applying voltages on those electrodes. The external electric field manipulates the refractive index of the medium in one, or more, polarizations. The medium must be transparent (or sufficiently so) to the incoming light and can be liquid crystal, an electro optical crystal, a quantum dot material or any other materials whose refractive index can be manipulated by applying an external electric field. Monochromatic light can be deflected if a sawtooth phase profile is provided. The inability to precisely control those electric fields due to fringing effects results in similar inability to rapidly change phase shifts, and an inability to create a sharp index change, and a sharp OPD change, therefore an inability to rapidly change OPD. The fly-back region reduces the fill factor of the optical grating where fill factor is defined as the percentage of the beam steered in the desired direction.

Fringing fields are the main reason for a fly-back region greater than zero. For liquid crystals there can also be an inability of the liquid crystal to change orientation quickly, but fringing fields are often a more limiting effect. FIG. 2 shows that during the fly-back portion of the phase profile the beam steers in the wrong direction. The following equation gives the efficiency due to fly-back effects.

$\begin{matrix} {\eta = \left( {1 - \frac{\Lambda_{F}}{\Lambda}} \right)^{2}} & \text{­­­Equation 1.} \end{matrix}$

In equation 1, ƞ is efficiency, Λ_(F) is the width of the fly-back region, and A is the width between resets. Equation 1 is taken from P. F. McManamon, T. A. Dorschner, D. C. Corkum, L. J. Friedman, D. S. Hobbs, M. K. O. Holz, S. Liberman, H. Nguyen, D. P. Resler, R. C. Sharp, and E. A. Watson, “Optical Phased Array Technology,” Proc. IEEE 84(2), 268-298, 1996. The McManamon reference “Optical Phased Array Technology”, which may be referred to as “Reference 4” hereinafter, is incorporated herein by reference in the entirety. This is the fringing field limited steering efficiency.

The following equation provides fly-back distance vs steering efficiency, for steering efficiency limited by fly-back.

$\begin{matrix} {\Lambda_{F} = \Lambda\left( {1 - \sqrt{\eta}} \right)} & \text{­­­Equation 2.} \end{matrix}$

FIG. 2 shows fringing fields make it impossible in a traditional thin steering device to impose an electric field that results in one electrode, or less, wide resets while using small electrodes and steering to large angles with commercially available materials having normal index change ratios. As a rule of thumb, the narrowest width of a reset is about the thickness of the device layer between the electrodes and the ground plane, as discussed in X. Wang, B. Wang, P. F. McManamon, J. J. Pouch, F. A. Miranda, J. E. Anderson, P. J. Bos, “Spatial resolution limitation of liquid crystal spatial light modulator,” Liquid Crystal Conference, Great Lakes Photonics Symposium, Cleveland, OH June 7-11, 2004. The Wang reference “Spatial resolution limitation...” is incorporated herein by reference in the entirety.

Fringing fields can have a significant limiting effect on presently known modulo 2π beam steering devices. For transmissive beam steering the cell must be at least approximately as thick as required to obtain one wavelength, or generate 2π phase, of OPD. A birefringence of 0.3 means the cell must be about 3.3 times one wavelength in thickness. Table 1 gives the fringing field effect on the steering efficiency for a 0.35 index of refraction change using transmissive beam steering. For electro-optic active materials having an index of refraction change lower than 0.35, the steering efficiency values will be lower than those depicted in Table 1.

TABLE 1 Efficiency vs. Angle limited by fringing field effects for previously known modulo 2π beam steering devices Angle (deg) Angle (rad) Index change Efficiency 20 0.349 0.35 0.0% 15 0.262 0.35 6.3% 10 0.175 0.35 25.0% 5 0.087 0.35 56.5% 2.5 0.044 0.35 76.4% 1.5 0.026 0.35 85.7% 1 0.017 0.35 90.5% 0.625 0.011 0.35 93.8% 0.25 0.004 0.35 97.7% 0.15 0.003 0.35 98.3% 0.1 0.002 0.35 98.9%

Table 1 shows that efficiency drops off rapidly for previously known modulo 2π beam steering at significant steering angles. If high efficiency is desired, then the steering angles used for previously known modulo 2π beam steering devices must be limited to very small angles. The fringing field efficiency losses are incurred for each steering event - for example if a 1 degree steering in both azmuith and elevation is performed, then the realized efficiency will be (.905)^2, or about 82% resulting efficiency. An example modulo 2π steering device consistent with the present disclosure utilizes a reflective beam steering, light goes into the device, bounces off a reflecting surface, and returns. As a result, the active device layer is half as thick and the fly-back region is half as wide, thus increasing the steering efficiency.

In certain embodiments, an optical phased array (OPA) non-mechanical beam steering includes the ability to point to less than 1/100^(th) of a diffraction limited angular spot size very accurately. For many applications, including high-energy applications and/or operations performed in sensitive areas, the ability to steer to the desired angles is very important. Modulo 2π beam steering using OPA technology can enable very precise steering, for example as explained in Reference 5.

Another factor is the steering efficiency due to quantization, which is described in the following equation from Reference 3:

$\begin{matrix} {\eta = \left\lbrack \frac{\sin\left( \frac{\pi}{q} \right)}{\left( \frac{\pi}{q} \right)} \right\rbrack^{2}} & \text{­­­Equation 3.} \end{matrix}$

In equation 3, ƞ is the steering efficiency, and q is the number of steps for each 2π phase shift progression of the steering device. Accordingly, eight (8) steps result in 95% steering efficiency from quantization, and ten (10) steps result in 96.8%. Any loss for quantization is additional loss compared to loss from fringing fields. Actual loss due to quantization for a few selected step values will be as shown in table 2:

TABLE 2 Quantization loss No of steps Efficiency 2 41% 3 68% 5 88% 6 91% 8 95% 10 96.8% 12 97.7% 16 98.7% 20 99.2%

Another background issue is the effect of magnification. A beam deflector having a small beam passing through it, when magnified, will decrease the steering angle, as shown in the following equation:

$\begin{matrix} {\vartheta_{f} = \frac{\vartheta_{i}}{M}} & \text{­­­Equation 4.} \end{matrix}$

In equation 4, ϑ_(ƒ) is the final steering angle, M is the magnification, and ϑ_(i), is the initial steering angle. For example, a 5 mm wide beam passing through a crystal and magnified to a 100 mm wide beam requires a magnification factor of 20. Therefore, a 10-degree steering angle is reduced to a half of a degree for this example with a magnification of 20.

Referencing FIG. 3 , a previously known bulk beam steering device is depicted to illustrate certain differences relative to various systems and methods in the present disclosure. In bulk beam steering, light passes through an EO crystal, and is steered. Under current practice, incident light with linear polarization in the proper direction is deflected and the angle of steering is varied by the application of an electric field. The angle of deflection for the conventional bulk beam deflector is calculated as:

$\begin{matrix} {\theta_{f} = \frac{L\Delta n}{W}} & \text{­­­Equation 5.} \end{matrix}$

In equation 5, θ_(ƒ) is the deflection angle, Δn is the index change occurred by the applied voltage and L and W are length and width of the rectangular beam deflector.

Previously known bulk beam steering devices suffer from a number of drawbacks. For example, when the optical beam is larger than a crystal, the beam is focused into the crystal and is expanded afterward. That requires large magnification, which reduces the effective steering angle as discussed preceding. Additionally, previously known bulk beam steering devices require significant voltages to be developed within the crystal, which may be thousands of volts. These high voltages are undesirable and introduce a number of challenges in management of the operating device, material selection and device design, and potential safety issues. The beam steered by a bulk beam steering device such as in FIG. 3 will likely be collimated when it traverses the crystal.

FIG. 4 depicts a previously known bulk beam steering device performing a two-dimensional beam steering using two bulk crystals, and a half waveplate between. In addition to the necessity of a half wave plate to rotate the polarization direction of the incident light by 90 degrees, some lenses may also be required between the two crystals to ensure the beam enters the second crystal.

As seen in FIG. 4 , one dimension will be steered first, possibly in one crystal, and then the other dimension will be steered, possibly in a second crystal. The linearly polarized light deflected in one-dimension travels through the second crystal to be steered in another dimension after its polarization direction is rotated by the half wave plate. Therefore, when the beam exits the first crystal it is deflected to a certain angle. That beam direction is maintained in the second crystal. A difficulty with this geometry is that the deflection angle must be kept small, or the beam will hit the side wall of the second crystal. The deflection of the beam inside of a crystal, resulting in the possibility of hitting the wall, is often called beam walk off by those practiced in the art.

Referring to FIG. 11 , an example modulo 2πn scanner comprises an active row made of an EO layer 3 (e.g., an EO active layer that changes an optical characteristic in response to an applied voltage) sandwiched between two sets of transparent discrete electrodes. The EO material may be any type of material that changes an optical characteristic in response to an applied voltage, including at least an EO crystal, a crystal layer, multiple crystal layers, an EO crystal layer, multiple EO crystal layers, a liquid crystal, a polymer, a quantum dot device, a crystal that responds to an applied electric field with a linear change in an index of refraction, and/or a crystal that responds to an applied electric field with a quadratic change in an index of refraction. An optical characteristic that changes in response to an applied voltage includes a change in birefringence and/or refractive index in response to an applied electric field. In certain embodiments the change may be dependent upon wavelength, polarization, and/or propagation direction of the steered EM beam. In certain embodiments, the change may be linear or non-linear. Without limitation to any other aspect of the present disclosure, it will be understood that descriptions utilizing an EO active layer, an active layer, an EO material, and/or a crystal may additionally or alternatively include any other EO active materials described throughout the present disclosure.

One of skill in the art, having the benefit of the disclosure herein, can readily select an appropriate EO material for a particular system. Certain considerations for material selection include, without limitation: the cost of materials, the steering capability (e.g., required electric field and/or optical change amount), the response time of the material in changing an optical characteristic, the cost of the material, fabrication considerations for the material (e.g., including available methods of fabrication, capability of the fabrication process for the material to achieve a particular design state, and/or cost of the fabrication process), the physical strength of the material as configured in a beam steering device, and/or thermal capability of the material (e.g., ability to withstand heat generation and/or support heat rejection). Certain considerations of a system when contemplating particular materials include, without limitation: the amount of steering desired; capital costs versus operating cost trade-offs; the energy throughput of the application; the available configurations for EM beam direction, polarization, and/or wavelength options; the desired accuracy and precision of beam steering direction, energy delivery, and/or optical characteristics of the steered beam; the availability of computing power in the device or accessible to the device to provide compensation, control, and/or analysis of electrical components and/or optical components in the device; and/or the size of the beam steering device (e.g., influencing the size of each layer, the number of layers, and/or the geometric configuration of the fabricated layer).

In the example of FIG. 11 , the upper electrodes 2 are high-side electrodes making up a high-side electrode layer, and the lower electrodes 4 are low-side electrodes making up a low-side electrode layer. In the example, the lower electrodes 4 may be at a ground state voltage, or another low voltage or baseline voltage value. The upper electrodes 2 may be at selected voltages thereby providing selected voltage differentials across the portions of the EO layer 3, thereby creating active cells of the EO layer 3. The EO layer 3 is interposed between two substrates 1 in the example of FIG. 11 . The description of upper electrodes 2 and lower electrodes 4 is an electrical description and not a geometrical description, and the upper electrodes 2 may be on a vertically upper side or vertically lower side of the EO layer 3, or an a side, oblique, or any other arrangement. In certain embodiments, one or more of the lower electrodes 4 may instead be a continuous or uniform electrode, such as a uniform ground electrode (e.g. reference FIG. 12 with ground electrode 670). In certain embodiments, the lower electrodes 4 (and/or uniform ground electrode 670) may be transparent, sufficiently transparent at selected EM wavelengths, reflective, and/or includes or is coupled with a reflective layer. In certain embodiments, the substrate 1 is transparent, sufficiently transparent at selected EM wavelengths, and/or includes or is coupled with a reflective layer. In the example of FIG. 11 , Light is propagating perpendicular to the substrate 1 through the EO crystal layer 3, and may progress through the upper electrodes 2 or the lower electrodes 4 first, and then through the other of the upper electrodes 2 or the lower electrodes 4 second..

Referring to FIG. 5 , an embodiment of this disclosure comprises a set of transparent discrete electrodes 30 and a ground electrode 40 located on opposite sides of an EO active layer 10. The ground electrode can be either reflective or transparent to the incoming light. Discrete electrodes 30 can be either conductive or resistive. The discrete electrodes may replace the uniform ground electrode 40 in some embodiments. Light is propagating perpendicular to the EO crystal layer 10, or at some angle with respect to the ground electrode 40, through the EO crystal layer 10, toward the discrete electrodes.

Note, the terms “crystal,” “EO crystal,” “crystal layer” and “EO crystal layer” are used interchangeably herein and refer to any media who’s index of refraction, or birefringence, can be changed by the application of an electric field. The crystals of this disclosure may include crystals with either a linear, or quadratic, change in index of refraction with respect to an applied field. The term crystals may also include liquid crystals, or any media whose index of refraction can be changed by application of an electric field. If transparent electrodes are used on both side of the structure shown in FIG. 5 , then to achieve larger steering angles one embodiment could use multiple stacked structures.

In FIG. 5 , Ground electrode 40 can be either transparent or reflective. In case of having transparent ground electrode 40, it may be a single electrode as shown, or may be a series of electrodes similar to discrete electrodes 30 located on the other side of the EO crystal layer 10. If the ground electrode 40 is a series of electrodes, said series of electrodes 40 do not have to all be set at zero voltage, even though the term ground is used.

The use of insulators 20 between electrodes 30 reduces the fly-back discussed in the background section for modulo 2π beam steering devices. This will allow steering to larger angles at high efficiency, because it will reduce the fringing field effects on the electric field. In certain embodiments, the insulators 20 may be a dielectric material, and/or include a dielectric material or layer as a part of the insulators 20. In previously known modulo 2π beam steering devices, there is significant spreading of the electric field, referred to as fringing fields, which is a primary contributor to the fly-back effect. The example embodiment of FIG. 5 , having the insulator 20 between electrodes 30, reduces the spreading of the electric field between electrodes. The transparent discrete electrodes 30 can be conductive or resistive. In both cases the fly-back distance will be reduced significantly but the phase diagram will be different whether those are conductive or resistive. As described preceding, FIG. 6 shows an example phase diagram and the sharp reset provided when discrete electrodes 30 are conductive, and FIG. 8 shows the phase diagram and the sharp reset provided when the discrete electrodes 30 are resistive discrete electrodes and/or electrodes configured to provide an optimum set of voltages across the active cells.

In one embodiment, the crystal layer 10 may have a resistivity that may be much lower than the insulator 20, for example 100 times lower. This is estimated to reduce the fringing electric field spreading effect by for example a factor of approximately 100 times in the insulator 20. The width of the insulator 20 can influence the amount of fringing field reduction. The quality of the insulator may also influence the amount of fringing field reduction, with a less conductive insulator providing more reduction in fringing fields. The insulator 20 may extend completely through the crystal layer 10 whose index can be changed by an electric field or the insulator 20 may only extend part way through the crystal layer 10. For example, the insulator 20 may extend anywhere from less than 10% to more than 80% through the crystal layer 10, or it can extend 100% of the way through the crystal. As a result, sharper resets are realized when the OPD is reduced during a reset from approximately a multiple of one wave, or a multiple of one wavelength, to approximately zero. Consequently, an OPD profile with sharper resets results, and higher steering efficiency is realized.

Comparing FIG. 2 with FIG. 6 shows that the electric field will increase in more discrete step increments than without the insulator 20 separating the discrete electrodes 30, rather than being smoothed by fringing fields, and the resets will be much sharper. An example embodiment utilizes partial penetration of the crystal layer 10 by the insulators 20 to retain and/or configure some smoothing of the fringing fields on the increasing phase ramp. An example embodiment utilizes partial penetration of the crystal layer 10 by the insulators 20 as a practical consideration in creating the insulators 20 within the crystal layer 10 - for example to enable easier fabrication and/or an improved mechanical structure of the beam steering device. In certain embodiments, insulators 20 provided at a reset position are enhanced (e.g., higher resistance and/or impedance, greater thickness, and/or a greater penetration of the crystal layer 10), providing for smoothing effects on the increasing phase ramp portion with greater fringing field resistance at a reset position.

Referring to FIG. 7 , another embodiment of this disclosure comprises tilted electrodes 50 instead of electrodes on the surface of the EO crystal layer 10. This embodiment will reduce, or eliminate, the quantization effect of the steps in building up the electric field. This embodiment further comprises an EO crystal layer 10, a ground electrode 40 and insulators 20. Ground electrode 40 includes, but is not limited to transparent ground electrodes. The transparent ground electrode 40 may be a single electrode as shown, or may be a series of electrodes. Once again, insulators 20 may extend fully or partially through EO crystal layer 10. The tilted electrodes 50 may progress in any configured manner through the EO crystal layer 10, as described throughout the present disclosure.

For the tilted electrode embodiment shown in FIG. 7 , the electric field on adjacent discrete tilted electrodes 50 is made continuous, or near continuous, by reducing the distance between the discrete electrodes 50 and the ground electrodes 40 using a fixed tilt angle. While the fixed electrode tilt angle may not be ideal for all steering angles, it will reduce the quantization effect over a wide range of steering angles. As shown in FIG. 8 , an increase in applied voltage is compensated by the distance change to provide a continuous, or near continuous, electric field at any adjacent discrete tilted electrode 50 before reset.

Another embodiment (not shown) using the insulators would be to implement modulo 2π beam steering using liquid crystals to cause a change in index of refraction. Any material that can have an index of refraction change in one polarization could be used with the insulators between conductive or resistive electrodes. The insulators can also be located between the electrodes with a depth between zero to the liquid crystal thickness, depending on the desired steering efficiency.

As seen in FIG. 9 and FIG. 10 , a mirror layer 60 can be added after the ground electrode layer 40 and/or as a layer on the substrate. If a stack of structures is used the mirror layer would be after the full stack of device layers. This will increase the deflection angle allowed at a certain steering efficiency by reducing the required cell thickness, and the fly-back region distance.

An example embodiment consistent with the depiction of FIG. 12 is described following. An embodiment comprises two optically active rows 610, 620 interposed between two substrates 600, 605. Each row contains an array of active cells 630 which active cells are separated from each other by insulator cells 640. The active cells 630 are made of an optically active material, and are sandwiched between a continuous ground electrode 650 and discrete electrodes 660. The discrete electrodes may be either conductive or resistive. The arrangement of active cells 630 and insulator cells 640 is opposite in each row. The size of an active cell 630 in a row 610, 620 is the same as the size of the corresponding insulator cell 640 in the next row. The last ground electrode 670 can be either reflective or transparent to the incoming light to be deflected by the scanner.

An example embodiment consistent with the depiction of FIG. 13 is described following. An embodiment depicted in FIG. 13 is similar to the embodiment shown in FIG. 12 but comprises four active rows 680, 685, 690 and 695. The four active rows 680, 685, 690 and 695 are interposed between two substrates 710 and 720. The embodiment can comprise any even number of active rows, and/or may include odd numbers of active rows, for example with one or more repeating rows. Each active row comprises a ground electrode 730, with the last ground electrode 700 being either reflective, or transparent, to the incoming light to be deflected by the scanner. Similar to the embodiment shown in FIG. 12 , each of the active rows contain an array of active cells 740. The active cells are separated from each other by insulator cells 750. The active cells 740 are made of an optically active material and are sandwiched between a continuous ground electrode 700, 730 and discrete electrodes 760, which may be either conductive or restrictive. The ground electrode could be in discrete elements in another embodiment. The arrangement of active cells 740 and insulator cells 750 is opposite in each row. The size of an active cell 740 in a row 680, 685, 690 and 695 is the same as the size of the corresponding insulator cell 750 in the next row. While FIG. 13 shows two pairs of rows, for a total of 4 rows, the number of rows may be any number, including any multiple of two rows or other arrangements.

An example embodiment consistent with the depiction of FIG. 14 is described following. An embodiment of a scanner comprises two optically active rows 770, 775 separated by a common transparent continuous ground electrode 780. Each of the active rows 770, 775 are interposed between two substrates 805, 807. Each row contains an array of active cells 790. The active cells 790 are separated from each other by insulator cells 800. The active cells are made of an optically active material and are sandwiched between a continuous ground electrode 780 and discrete electrodes 810, which may be either conductive or resistive. The arrangement of active cells 790 and insulator cells 800 is opposite in each row. The size of an active cell 790 in a row 770, 775 is the same as the size of the corresponding insulator cell 800 in the neighboring row. A reflective layer 820 can be located on a surface of the substrate 805 to make the scanner reflective.

An example embodiment consistent with the depiction of FIG. 15 is described following. An embodiment of a scanner depicted in FIG. 15 is similar to the embodiment shown in the FIG. 14 but comprises four active rows 830, 840, 850, and 860 instead of just two active rows. The embodiment can comprise any even number of active rows, and/or may include odd numbers of active rows, for example with one or more repeating rows. Each two rows are separated by a transparent continuous ground electrode 780 and each pair of rows is interposed by two substrates. More specifically, a first pair of rows is interposed between substrates 870 and 872 and a second pair of rows is interposed between substrates 872 and 875, as shown in FIG. 15 . Each row contains an array of active cells 790. The active cells 790 are separated from each other by insulator cells 800. The active cells are made of an optically active material and are sandwiched between a continuous ground electrode 780 and discrete electrodes 810, which may be either conductive or resistive. The arrangement of active cells 790 and insulator cells 800 is opposite in each row. The size of an active cell 790 in a row is the same as the size of the corresponding insulator cell 800 in the neighboring row. A reflective layer 890 may be located on a surface of the substrate 870 to make the scanner reflective. While FIG. 15 shows two pairs of rows, for a total of 4 rows, the number of rows may be any number, including any multiple of two rows or other arrangements.

In FIGS. 12 - 15 , the light is initially propagating perpendicular to the substrate through the active cells, toward the discrete electrodes, or at some initial input angle to perpendicular. In FIGS. 12 - 15 , the discrete electrodes can be either conductive or resistive. In the case of conductive discrete electrodes, only one voltage at the same time is applied on each discrete electrode and a reset will usually contain eight or more discrete electrodes in order to achieve 95% steering efficiency, or better, based on quantization loss. In case of resistive electrodes, two, or more, different voltages at the same time may be applied on each discrete electrode, and a reset may contain only one or more discrete electrodes. Moreover, in the embodiments depicted in FIGS. 12 - 15 , the active cells are made of any transparent material whose refractive index can be changed by applying voltages on the discrete electrodes., Such transparent materials include but are not limited to EO crystals like PMN-PT, KTN, SBN, PBN, PZT, BaTiO₃, liquid crystals, and/or quantum dot materials.

Referencing FIG. 16 , an example embodiment of a beam steering device is depicted. The example of FIG. 16 includes two active layers, with an EO active material 1606 providing a number of active cells, each active cell positioned between one of a number of discrete high-side electrodes 1610 and a low-side electrode 1612 (depicted as a common ground electrode in the example of FIG. 16 ). The example beam steering device includes insulators 1608 positioned between each of the high-side electrodes 1610, and a substrate 1602, 1604 provided on each side of the active layer. The example of FIG. 16 may additionally include more active layers, and the substrate 1602, 1604 may be positioned between each active layer and/or book-end the active layers. The example of FIG. 16 is similar to a Chess Pattern beam steering device, with offset active cells in adjacent active layers, such that an incident EM beam passes through one or the other of the active layers. FIG. 16 includes a bridging portion 1614 of the EO active material 1606 across the insulation region (1608), which may provide for ramp smoothing of the progressive phase delay, and/or may provide for easier fabrication and/or improved mechanical properties of the beam steering device.

Referencing FIG. 17 , an example embodiment of a beam steering device is depicted. The example of FIG. 17 includes two active layers, with an EO active material 1706 providing a number of active cells, each active cell positioned between one of a number of discrete high-side electrodes 1710 and a low-side electrode 1712 (a shared common ground electrode in the example of FIG. 17 ). The example beam steering device includes insulators 1708 positioned between each of the high-side electrodes 1710, and a substrate 1702, 1704 provided on each side of the active layer. The example of FIG. 17 further includes a reflective layer 1716. The example of FIG. 17 may additionally include more active layers, and the substrate 1702, 1704 may be positioned between each active layer and/or book-end the active layers. The example of FIG. 17 is similar to a Chess Pattern beam steering device, with offset active cells in adjacent active layers, such that an incident EM beam passes through one or the other of the active layers. FIG. 17 includes a bridging portion 1714 of the EO active material 1706 across the insulation region (1708), which may provide for ramp smoothing of the progressive phase delay, and/or may provide for easier fabrication and/or improved mechanical properties of the beam steering device.

Referencing FIG. 18 , an example embodiment of a beam steering device is depicted. The example of FIG. 18 includes one active layer providing approximately 100% fill efficiency within a single active layer. The example of FIG. 18 includes an EO active material 1806 providing a number of active cells, each active cell positioned between one of a number of discrete high-side electrodes 1810, 1811 and a low-side electrode 1812 (a common ground electrode in the example of FIG. 18 ). The example beam steering device includes a substrate 1804 - in the example of FIG. 18 , the substrate 1804 provides an insulating function for the active layer, and portions of the substrate 1804 positioned between high-side electrodes 1810 may be considered insulators as described throughout the present disclosure. The example of FIG. 18 further includes a substrate 1802 opposing the substrate 1804, and a reflective layer 1816 coupled to the substrate 1804. The example of FIG. 18 includes a number of active cells formed from a single active EO substrate 1806, having varying thicknesses 1818, 1820. An example beam steering device includes the first thickness 1818 being a wavelength of a target EM beam, one-half of a wavelength of the target EM beam (e.g., in embodiments having a reflective layer 1816), and/or being a discrete number of wavelengths and/or half wavelengths of the target EM beam. The example beam steering device further includes the second thickness 1820 being at least one-half wavelength greater than thickness 1818, or one full wavelength greater than thickness 1818. In certain embodiments, thickness 1818 is one wavelength (λ), and thickness 1820 is two wavelengths (2λ). In certain embodiments, the voltage applied across each active cell is adjusted to provide the desired phase delay profile, and/or the width of the active cells having varying thicknesses 1818, 1820 is varied to provide the desired phase delay profile. In certain embodiments, a beam scanner having two (or more) active thicknesses within a single active layer, such as depicted in FIG. 18 , is described as a Castle Scanner and/or Castle Pattern. In certain embodiments, where resistive high-side electrodes 1810, 1811 are utilized with a Castle Pattern, such a beam scanner is described as a Castle Scanner Pro or a Castle Pattern Pro. The terminology of Castle Scanner or Castle Scanner Pro embodiments is used for convenience and clarity of the description herein. The example of FIG. 18 provides for a number of advantages in certain embodiments of the present disclosure, including a simplification of fabrication of the beam steering device, enhanced mechanical integrity of the beam steering device, and/or a smaller vertical footprint of the scanner (e.g., along the axis of propagation of the incident EM beam) for a given steering capability.

The present disclosure throughout provides for specific examples for clarity of description and to show the inter-operability of various features of the disclosure. Embodiments described may be combined in whole or part, and/or certain described features may be omitted, according to the capabilities desired for a particular system. For example, resistive electrodes may be utilized for some or all of the high-side electrodes in any of the described embodiments. Active cell thicknesses may be progressed and may vary in any active layer, or between active layers, in any of the described embodiments. Insulators may be provided as an explicit device (e.g., as in FIGS. 12 or 16 ) and/or may be included as an air gap or a substrate portion (e.g., as in FIG. 18 ). Low-side electrodes may be at any voltage value, including a baseline or zero reference voltage, any voltage lower than the high-side electrodes (during steering operations), and/or at a negative reference voltage. Electrodes may be provided as tilted or contoured electrodes in one or more portions of the beam steering device, or throughout the beam steering device. All or portions of the beam steering device may be provided as a Chess arrangement, a Castle arrangement, or any other arrangement described throughout the present disclosure.

The present disclosure describes active layers steering an incident EM beam. It is understood that the steering of the EM beam may be in a single direction (e.g., X or Y, azimuth or elevation, etc.) and/or for a single polarity of the EM beam, and that additional layers may be provided to include additional steering in other directions, in another polarity, and/or to provide incremental steering for the first direction and/or polarity.

Referencing FIG. 19 , an example controller 1902 structured to perform certain operations for steering multiple EM wavelengths is schematically depicted. The controller 1902 is depicted as a single device for clarity of description, although aspects of the controller 1902 may be distributed across multiple devices, implemented in hardware and/or as instructions stored on a computer readable medium, as sensors or actuators present in the system, and/or through network communications and/or remote processing capabilities.

An example controller 1902 includes a number of circuits structured to functionally execute certain operations of the controller 1902. Certain operations are described in specific reference to FIG. 19 , but any operations, procedures, or techniques throughout the present disclosure may be implemented by, or performed by, a controller such as controller 1902. The example controller 1902 includes an incident wavelength circuit 1904 that determines a wavelength value 1906 of an incident EM beam, a steering configuration circuit 1908 that determines a first EO layer command value 1910 and a second EO layer command value 1912 in response to the incident EM beam. A given system may include any number of EO layers, and/or an EO layer may be a logical arrangement of active cells within one or more physical layers, for example with an area of active cells distributed across multiple physical layers making up an EO layer. An EO layer command may include multiple commands to be provided to multiple electrodes, including voltage commands to high-side electrodes, and/or pull-down commands to low-side electrodes (e.g., where one or more low-side electrodes are pulled to a lower voltage during steering operations), such that a selected phase delay progression is provided across the EO layer when the EO layer commands are executed. In certain embodiments, EO layer commands further include a timing value that coordinates the EO layers - for example when the controller 1902 is steering multiple EM wavelengths in a sequenced and/or pulse-width modulated (PWM) operation. The example controller 1902 further includes a steering implementation circuit 1914 that provides at least one of the first EO layer command value 1910 or the second EO layer command value 1912 to a steering control module 1916.

Operations of the controller 1902 may be performed during run-time or design time, or a combination of these. For example, where the wavelength of the incident EM beam to be steered is predetermined, operations of the incident wavelength circuit 1904 may be performed at design time, for example in the material selection and configuration of active cells, the geometry of active cells, the thickness of the EO layer, the utilization (or not) of a reflective layer, the selected parameters for insulators, and the design voltages of the electrodes (high-side and/or low-side). In the example, the EO layer commands 1910, 1912 may be predetermined for the selected wavelength, and the operations of the steering configuration circuit 1908 include providing a lookup of the EO layer commands 1910, 1912 (e.g., considering the wavelength value 1906, the configurations of one or more EO layers in the system, and/or the amount and direction of steering that is commanded). In the example, the steering implementation circuit 1914 provides the EO layer commands 1910, 1912 to the steering control module 1916 when the incident EM beam is active, during selected operating periods, and/or continuously. In the example, the steering control module 1916 controls the electrode voltages to implement the EO layer commands 1910, 1912 in response to the commands provided by the steering implementation circuit 1914.

In another example, such as when the wavelength of the incident EM beam is configurable, selectable, and/or varies after initial construction of the beam steering device (e.g., to support multiple steering configurations with a single hardware device, and/or to steer multiple EM beam wavelengths with a single hardware device), one or more operations of the incident wavelength circuit 1904 may be performed at run-time. In the example, the incident wavelength circuit 1904 determines the wavelength value 1906 at run-time, for example using any sensing technique known in the art, and/or by determining that another system parameter is indicating that a particular wavelength value 1906 is being utilized (e.g., a network parameter, a parameter provided by another controller, an active state of a particular EM source, or the like). In the example, the steering configuration circuit 1908 determines the EO layer commands 1910, 1912 (e.g., considering the wavelength value 1906, the configurations of one or more EO layers in the system, and/or the amount and direction of steering that is commanded). In the example, the steering control module 1916 controls the electrode voltages to implement the EO layer commands 1910, 1912 in response to the commands provided by the steering implementation circuit 1914.

Certain examples of operations of the controller 1902 are provided for clarity of the present description. It will be understood that operations of the controller 1902 may be provided in any combination of design-time and/or run-time operations, and further that operations of the controller 1902 may be adjusted in response to the operating conditions of the system, a change in the application of the beam steering device including the controller 1902 (e.g., a change in the steered wavelength, a change in the desired steering capability, and/or a change in the timing of multiple-layer steering operations), and/or in response to a change in a hardware configuration of the beam steering device (e.g., a change in the EO layer, voltages of the system, and/or a wavelength of an EM source).

An example steering control module 1916 provides selected voltages to at least one of the first high-side electrode layer or the second high-side electrode layer in response to the at least one of the first EO layer command value 1910 or the second EO layer command value 1912. An example steering control module 1916 further includes a solid state circuit that applies selected voltages to each electrode of the first high-side electrode layer and the second high-side electrode layer. An example solid state circuit further selectively couples a power source to each electrode of the first high-side electrode layer and the second high-side electrode layer, and/or selectively couples the power source using a pulse-width modulation (PWM) operation. In certain embodiments, a steering control module 1916 includes hardware elements configured to execute operations to implement the EO layer command values 1910, 1912, for example solid state switches that are responsive to commands from the steering implementation circuit 1914. In certain embodiments, the steering control module 1916 may be a smart controller, structured to provide commands to implement the EO layer command values 1910, 1912 as provided by the steering implementation circuit 1914. In certain embodiments, aspects of the steering control module 1916 may be implemented on the controller 1902. Accordingly, it will be seen that the EO layer command values 1910, 1912 may vary, from low-level hardware commands (e.g., ON/OFF, or a voltage value sourced from or switched from the controller 1902) to high-level steering commands (e.g., steer 5 degrees in the X axis with EO layer 2, and 7 degrees in the Y axis with EO layer 3), combinations of these, and/or intermediate parameters between these (e.g., voltage values indicating an amount of steering and/or a layer to be controlled, simple state values which the steering control module 1916 is configured to be responsive to, or the like). In certain embodiments, the steering control module 1916 may receive the EO layer command values 1910, 1912 as physical values (e.g., voltages, frequencies, pressures, or another physical value), as network communicated parameters from the controller 1902, and/or as parameters retrieved from the controller 1902 memory by the steering control module 1916 (e.g., in a selected memory location that is populated by the steering implementation circuit 1914). The example steering control module 1916 hardware and operational examples are non-limiting, and provided for clarity of the present description.

In certain embodiments, EO active layers having thick and thin elements are referenced as a castle configuration herein. In certain embodiments, a castle configuration includes both the thick and thin elements making up active cells of the beam steering device (e.g., having an associated discrete high-side electrode). In certain embodiments, a castle configuration includes adjacent physical layers of the beam steering device having alternating thick and thin elements, such as that depicted in FIG. 16 . In certain embodiments, a beam steering device in a castle configuration having one or more resistive high-side electrodes may be referenced as a castle pro configuration herein.

In certain embodiments, EO active layers having alternating active cells are referenced as a chess configuration herein. In certain embodiments, a chess configuration includes adjacent physical layers of the beam steering device alternating such that an incident EM beam passes through one or the other of the active cells from one of the EO active layers. In certain embodiments, a chess configuration includes active cells from adjacent layers being sized the same (e.g., thickness, width, or both). In certain embodiments, a beam steering device in a chess configuration having one or more resistive high-side electrodes may be referenced as a chess pro configuration herein.

Referencing FIG. 20 , an example apparatus 1902 includes an incident beam circuit 2002 that interprets an EM beam value 2004 (e.g., a wavelength and/or frequency of an incident EM beam to a beam steering device), a steering request circuit 2006 that interprets a steering profile value 2008, and a steering configuration circuit 1908 that determines a number of voltage values 2010 in response to the steering profile value 2008. In certain embodiments, the steering request circuit 2006 determines the steering profile value 2008 in response to the EM beam value 2004 and/or a steering request value 2012. An example steering profile value 2008 includes steering instructions (e.g., wavelengths and/or polarities to be steered, and a steering direction that may be determined in response to a steering target location and/or a steering amount). An example steering configuration circuit 1908 determines the number of voltage values 2010 in response to the steering profile value 2008 – for example determining voltage values 2010 that provide configurations of active cells of a beam steering device to steer an incident EM beam in a manner consistent with the steering profile value 2008.

In certain embodiments, the number of voltage values 2010 correspond to a number of active cells of an EO material, where the number of voltage values 2010 include at least one progressive voltage value and a voltage reset value (e.g., a voltage trajectory across one or a number of active cells, and a voltage reset value that resets at each active cell and/or after a selected number of active cells). The example apparatus 1902 further includes a steering implementation circuit 1914 that provides an EO command value 1910 in response to the number of voltage values 2010.

Certain further aspects of an example apparatus are 1902 described following, any one or more of which may be present in certain embodiments. An example apparatus 1902 includes where the voltage reset value includes a voltage adjustment between two adjacent ones of the number of active cells to apply a 2πn phase shift between a first one of the adjacent ones of the active cells and an second one of the adjacent ones of the of active cells, where n includes a small positive integer value. An example steering profile value 2008 includes: a target location for an EM beam; a target steering angle for an EM beam; a first target steering angle for a first steering axis for an EM beam and a second target steering angle for a second steering axis for the EM beam; and/or any of the foregoing for a selected polarity of the EM beam. An example EM beam value 2004 includes at least one EM beam value such as: a wavelength value of an incident EM beam, a presence of an incident EM beam, and a characteristic of an incident EM beam (e.g., a polarity, energy level, timing value, incident angle, or the like). An example apparatus 1902 includes the steering configuration circuit 1908 further determining the number of voltage values 2010 for a number of layers of active cells of the EO material. In certain embodiments, the steering implementation circuit 1914 provides the EO command value(s) 1910 to a device to implement the beam steering, for example to a steering control module 1916.

The following descriptions reference schematic flow diagrams and schematic flow descriptions for certain procedures and operations according to the present disclosure. Any such procedures and operations may be utilized with and/or performed by any systems of the present disclosure, and with other procedures and operations described throughout the present disclosure. Any groupings and ordering of operations are for convenience and clarity of description, and operations described may be omitted, re-ordered, grouped, and/or divided, in whole or part, unless explicitly indicated otherwise.

Referencing FIG. 21 , an example procedure 2100 includes an operation 2102 to receive an incident electro-magnetic (EM) beam at a multi-layer beam steering device, an operation 2104 to determine a wavelength value of the incident EM beam, and an operation 2106 to selectively steer the EM beam with a first layer or a second layer of the multi-layer beam steering device in response to the determined wavelength value of the incident EM beam.

Certain further aspects of an example procedure are described following, any one or more of which may be present in certain embodiments. An example procedure further includes the operation 2106 to selectively steer by: applying selected voltages to a selected one of the first layer or the second layer, applying a voltage gradient across the selected one of the first layer or the second layer, and/or by applying resets at selected intervals across the selected one of the first layer or the second layer. An example procedure further includes an operation 2108 to determine a selection frequency of interest, and an operation 2110 to alternate the wavelength value of the incident EM beam at a frequency at least equal to the selection frequency of interest.

Referencing FIG. 22 , an example procedure 2200 includes an operation 2102 to receive an incident electro-magnetic (EM) beam at a number of active cells of an electro-optic (EO) material; an operation 2202 to apply a voltage to the number of active cells, thereby selectively adjusting an optical characteristic of each of the number of active cells; and an operation 2204 to reset a voltage between at least two adjacent ones of the number of active cells, thereby steering the incident EM beam. In certain embodiments, the number of active cells between reset operations 2204 is a single active cell - for example where resistive high-side electrodes, tilted electrodes, and/or other configurations described throughout the present disclosure provide for a configuration where a voltage gradient can be applied across a single active cell. In certain embodiments, even where a voltage gradient can be applied across a single active cell, the operation 2204 to reset the voltage may be performed after a number of active cells greater than one (1) cell, for example, where a voltage gradient is continued into a second cell (e.g., to reduce the number of resets across the beam steering device, to keep a voltage gradient across a single cell below a selected value, to keep a voltage gradient across a single cell within a linear or other selected region for a conductive resistor, etc.).

Certain further aspects of an example procedure 2200 are described following, any one or more of which may be present in certain embodiments. An example procedure includes the operation 2204 to reset the voltage including one or more of: resetting the voltage by an amount to apply a 2π phase shift between a first one of the number of active cells and an adjacent second one of the number of active cells; resetting the voltage by an amount to apply a 2πn phase shift between a first one of the number of active cells and an adjacent second one of the number of active cells, where n includes a small positive integer value; and/or resetting the voltage to a value applying a negative phase shift. An example procedure 2200 further includes operation 2202 to apply the voltage to the number of active cells to: apply a progressive phase shift to the incident EM beam; and/or to apply the progressive phase shift by applying progressive voltages to adjacent ones of the number of active cells, and resetting the progressive voltages at selected intervals of the number of active cells. In certain embodiments, the selected intervals of the number of active cells between resets include at least six (6) of the number of active cells in each of the selected intervals. In certain embodiments, operation 2202 to apply the voltage to the number of active cells includes: applying a uniform voltage to each of the number of active cells, and further applying a distinct uniform voltage to adjacent ones of the number of active cells; applying a voltage gradient to each of the number of active cells; and/or applying a distinct voltage gradient to adjacent ones of the number of active cells.

An example procedure 2200 further includes an operation 2206 to insulate a first high side electrode corresponding to a first one of the number of active cells from a second high side electrode corresponding to a second one of the number of active cells, where the first one of the number of active cells is adjacent to the second one of the number of active cells. In certain embodiments, the operation 2206 includes enhancing the insulating in response to the first one of the number of active cells and the second one of the active cells including the at least two of the number of active cells corresponding to the resetting the voltage (e.g., providing enhanced insulating between a final active cell of a first progressive phase delay stage having a maximum phase shift/voltage, and an initial active cell a second progressive phase delay stage having a minimum phase shift/voltage). An example procedure 2200 further includes an operation 2208 to steer the incident EM beam in a first axis, thereby providing a first axis steered EM beam. In certain embodiments, the procedure 2200 further includes an operation 2210 to determine whether additional axes and/or additional polarities of the incident EM beam are to be steered, and to repeat operations 2102, 2202, 2204, and 2206, thereby steering the in a second axis and/or a second polarity. For example, procedure 2200 further includes, in response to operation 2210 determining YES, an operation 2102 to receive the first steered EM beam (e.g., from a previous iteration of procedure 2200) at a second number of active cells of the EO material, an operation 2202 to apply a voltage to the second number of active cells, thereby selectively adjusting an optical characteristic of each of the second number of active cells; and/or an operation 2204 to reset a voltage between at least two adjacent ones of the second number of active cells, thereby steering the incident EM beam in a second axis (and/or second polarity) distinct from the first axis (and/or first polarity). In certain embodiments, procedure 2200 further includes an operation 2206 to insulate a first high side electrode corresponding to a first one of the second number of active cells from a second high side electrode corresponding to a second one of the second number of active cells, where the first one of the second number of active cells is adjacent to the second one of the second number of active cells. It can be seen that the operations of the example procedure 2200 provide a two-axis steered and/or two-polarity steered EM beam.

Referencing FIG. 23 , an example procedure 2300 includes an operation 2302 to interpret an electro-magnetic (EM) beam value, an operation 2304 to interpret a steering profile value, and an operation 2306 to determine a number of voltage values in response to the steering profile value. The number of voltage values correspond to a number of active cells of an EO material, and the number of voltage values include at least one progressive voltage value and a voltage reset value. In certain embodiments, progressive voltage values may be within an active cell, and/or stepped between active cells. The example procedure 2300 further includes an operation 2308 to provide an EO command value in response to the number of voltage values.

Certain further aspects of an example procedure are described following, any one or more of which may be present in certain embodiments. An example procedure 2300 further includes: where the voltage reset value includes a voltage adjustment between two adjacent ones of the number of active cells to apply a 2πn phase shift between a first one of the adjacent ones of the active cells and a second one of the adjacent ones of the of active cells, where n includes a small positive integer value. An example steering profile value includes a target location for an EM beam and/or a target steering angle for the EM beam; where the steering profile value includes a first target steering angle for a first steering axis for an EM beam and a second target steering angle for a second steering axis for the EM beam; where the steering profile value includes a first target steering angle for a first polarity of the EM beam and a second target steering angle for a second polarity of the EM beam; and/or where the EM beam value includes at least one EM beam value such as: a wavelength value of an incident EM beam, a presence of an incident EM beam, and a characteristic of an incident EM beam. An example procedure 2300 further includes the operation 2306 to determine the number of voltage values for a number of layers of active cells of the EO material.

Referencing FIG. 24 , an example procedure 2400 includes an operation 2402 to provide an EO layer including an EO active material, and an operation 2404 to form a number of active cells of the EO layer, where the forming includes: operationally coupling a high-side electrode layer including a number of discrete electrodes to a first side of the EO layer; and operationally coupling a low-side electrode layer to a second side of the EO layer. The example procedure 2400 further includes an operation 2406 to operationally couple an insulator to the number of active cells of the EO layer, where the insulator is at least partially positioned between a first one of the active cells and a second one of the active cells.

Certain further aspects of an example procedure 2400 are described following, any one or more of which may be present in certain embodiments. An example procedure 2400 further includes: operation 2402 including providing the EO layer in a castle configuration; operation 2402 including providing a number of EO layers in a chess configuration; operation 2404 including operationally coupling the high-side electrode layer by providing the number of discrete electrodes as resistive electrodes; operation 2404 including operationally coupling the high-side electrode layer by providing the number of discrete electrodes as tilted electrodes; and/or operation 2404 including operationally coupling the high-side electrode layer by providing the number of discrete electrodes as electrodes having a selected geometric arrangement. An example procedure 2400 further includes: operation 2402 including providing the EO layer by providing a number of EO layers, and operation 2404 further including forming the number of active cells of the EO layer by operationally coupling each one of a number of high-side electrode layers to a corresponding one of the number of EO layers; and/or operation 2404 further including forming the number of active cells of the EO layer by operationally coupling a low-side electrode layer such that the low-side electrode layer is shared by adjacent ones of the number of EO layers. An example procedure 2400 further includes: operation 2402 further including providing the EO layer by utilizing a contiguous substrate of the EO material for the EO layer; operation 2406 further including operationally coupling the insulator by utilizing a contiguous substrate of insulator material for the insulator; operation 2404 further including operationally coupling the low-side electrode layer by utilizing a reflective low-side electrode layer; operation 2404 further including operationally coupling the high-side electrode layer by providing the number of discrete electrodes as resistive electrodes having a selectable resistance profile; and/or operation 2404 further including providing the number of discrete electrodes as resistive electrodes having a selectable resistance profile by providing the number of discrete electrodes as solid state electrodes.

Referencing FIG. 25 , an example procedure 2500 for implementing an improved modulo 2πn electro-optical or photonic beam steering scanner includes an operation 2502 to provide a modulo 2πn electro-optical or photonic beam steering scanner, an operation 2504 to introducing a beam of light to at least one active EO crystal layer of the scanner, and an operation 2506 to impose one or more voltages on conductive or resistive discrete electrodes of the scanner to change an index of refraction sufficient to cause an OPD change to the beam of light traveling through the scanner.

Without limitation to any other aspect of the present disclosure; a first example improved modulo 2πn electro-optical or photonic beam steering scanner usable with procedure 2500 includes at least one active EO layer having a first side and an opposing second side; at least one conductive or resistive discrete electrode, arranged along the first side; at least one ground electrode arranged along the second side, and at least one insulator arranged to extend at least partially into the active EO layer; and a second example improved modulo 2πn electro-optical or photonic beam steering scanner usable with procedure 2500 includes at least two active rows arranged between two substrates, the substrates transparent to an incoming optical or photonic wave, each active row having a first side and an opposing second side, where each active row includes at least two active cells separated by at least one insulator cell, at least one ground electrode arranged between two of the at least two active rows; each of the at least two active rows having at least one discrete conductive or resistive electrode arranged along the first side or second side of each active row opposite the at least one ground electrode; and where an arrangement of the at least two active cells and insulator cells in one of the at least two active rows is opposite to the arrangement of the at least two active cells and insulator cells in the other of the at least two active rows.

Referencing FIG. 26 , an example beam steering device is depicted. The example beam steering device includes a hardware layer 2602 having beam steering components, including a high-side electrode layer 2606, a low-side electrode layer 2610, and a number of active cells 2608. The active cells 2608 are positioned between the high-side electrode layer 2606 and the low-side electrode layer 2610, and include an EO active material that changes an optical characteristic in response to an applied voltage or electric field. The example beam steering device may include the EO active material that makes up the substrate of the active cells 2608 provided as discrete elements of the EO active material, or as a monolithic substrate, where portions of the monolithic substrate interposed between each discrete electrode of a number of discrete electrodes of the high-side electrode layer 2610 each form one of the active cells. In certain embodiments, segments of the EO active material may form several active cells 2608, with the EO active material formed in more than one segment to create the active cell layer.

The example beam steering device further includes a voltage controller 2612 responsive to voltage commands, steering commands, or other similar command structures, where the voltage controller 2612 provides voltage control of elements of the high-side electrode layer 2606 and/or the low-side electrode layer 2610, thereby controlling the voltage differential and/or electric field across the active cells 2608. In certain embodiments, voltage control of the electrode layers 2606, 2610 includes raising the voltage of the high-side electrode layer 2606 and/or individual discrete electrodes of the high-side electrode layer 2610, and may further include lowering the voltage (and/or connecting to a ground) of the low-side electrode layer 2610 and/or individual discrete electrodes of the low-side electrode layer 2610. In certain embodiments, the hardware layer 2602 of the example beam steering device may include any features and/or elements of any beam steering device throughout the present disclosure, including without limitation: insulators interposed (at least partially) between one or more of the active cells 2608; electrodes provided as discrete or continuous electrode layers (e.g., where at least one of the high-side electrode layer 2606 or the low-side electrode layer 2610 is provided as discrete electrodes, and/or where each of the active cells 2608 is provided with a discrete electrode at the high-side or low-side to provide for individual voltage differential control for that active cell); tilted and/or geometrically profiled electrodes; the active cells provided in a castle arrangement, a chess arrangement, or combinations of these; a reflective layer or reflective element (e.g., a substrate or ground electrode provided as a reflective layer, and/or a reflective layer associated with one of these); and/or an anti-reflective coating provided on at least a portion of a layer interface in the hardware layer 2602. In certain embodiments, the hardware layer 2602 includes multiple layers of active cells structured to cooperate to provide one or more of: steering for more than one polarity; more than one axis; more than one target wavelength of an incident EM beam 2604; additional steering capability; and/or to cooperate among distinct hardware layers of active cells for steering a particular wavelength, polarity, and/or axis.

In certain embodiments, the discrete electrodes 2606 are sized such that a length of an individual discrete electrode 2606 (e.g., the left-right distance of the discrete electrode 2606) is the same as, or similar to, a thickness of the active cells 2608. In certain embodiments, the ratio of the length of individual discrete electrodes 2606 to the thickness of the active cells 2608 is referenced as the aspect ratio. It has been found that having a discrete electrode 2606 that is the same as the thickness of the active cell 2608 (e.g., providing an aspect ratio of about 1) minimizes (but does not eliminate) fringing fields between electrodes 2606. In certain embodiments, and without limitation, a length of the discrete electrode 2606 that is the same as, or similar to, the thickness of the active cells 2608 (e.g., having an aspect ratio of about 1) includes: the length and thickness being nominally the same (e.g., allowing for variances and tolerances from manufacturing and assembly processes, and part-to-part variation); a length and thickness being selected such that fringing fields are within a selected amount (e.g., a ratio, an offset value, below a maximum threshold, etc.) of a minimum fringing field value; a closest match between the length and thickness available from nominally available parts (e.g.: off-the-shelf or commercially available electrodes and/or EO materials; a closest match from available electrodes and/or EO materials from other systems already in production; and/or a closest match of electrodes and/or EO materials selected from a range of materials designed for other considerations (e.g.: the sizing of the beam steering device; the number of progressive phase delay stages and the number of phase delay steps in each stage; the mechanical integrity of the beam steering device; and/or the heat transfer environment and/or heat rejection environment of the beam steering device). In certain embodiments, certain electrodes 2606 may have a same or similar length as the thickness of the active cells, and other electrodes 2606 may not have a same or similar length as the thickness of the active cells. For example, electrodes 2606 positioned at a reset position (e.g., the last electrode of a first stage, and/or the first electrode of a second stage) may be sized to be in closer correlation to the same length as the thickness of the active cells relative to other electrodes 2606 in the same beam steering device. In another example, certain electrodes 2606 may be separated by insulators (and/or more capable insulators), while other electrodes 2606 are not separated by insulators (and/or less capable insulators), with un-insulated electrode 2606 separations having an aspect ratio closer to 1, and insulated electrode 2606 separations having an aspect ratio further from 1. It can be seen that the electrode 2606 length and/or active cell thickness 2608 can be tuned to provide a desired fringing field profile across the beam steering device, for example to utilize fringing fields to smooth the phase profile (e.g., reference FIG. 8 ) while minimizing fringing field losses, such as at high loss regions like the reset position.

It can be seen, in view of the various embodiments of the present disclosure, that in certain embodiments, electrode 2606 lengths such as λ, ½λ, and/or ¼λ, as well as integer multiples of these, may be desirable to match the varying thicknesses of active cells 2608, either within a beam steering device, within a beam steering device layer (e.g., where different layers are provided to steer distinct wavelengths), or between different devices. For example, in a beam steering device where steering efficiency is a paramount concern, a close match of electrode 2606 lengths to active cell 2608 thicknesses may be provided, and in a beam steering device where a smooth phase delay profile is desired, the match of the electrode 2606 length to active cell 2608 thickness may be relaxed - even where the beam steering devices otherwise are configured to steer a same wavelength of an incident EM beam to a same steering direction capability.

The example beam steering device further includes a steering controller 2616 that provides steering commands to the hardware layer 2602. The voltage controller 2612 is responsive to the steering commands to provide the voltage control of elements of the electrode layers 2606, 2610, thereby directing the incident EM beam 2604 to the desired location as a steered EM beam 2614. In certain embodiments, the steering controller 2616 and/or the voltage controller 2612 include any aspects, and/or are configured to perform any operations, as referenced throughout the present disclosure to perform beam steering operations. Without limitation to any other aspects of the present disclosure, the steering controller 2616 and/or the voltage controller 2612 may include any aspects or perform any operations of a controller 1902, and/or may perform any operations as recited in the disclosure referencing FIGS. 21-25 , and/or any operations recited in the disclosure reference FIG. 31 .

Referencing FIG. 27 , an example beam steering device includes the high-side electrode layer 2606, the low-side electrode layer 2610, and the active cells 2608. In the example of FIG. 27 , the high-side electrode layer 2606 is provided as a number of discrete electrodes, the low-side electrode layer 2610 is provided as a common ground electrode, and the active cells 2608 include portions of a monolithic EO active substrate layer that are positioned between each of the discrete high-side electrodes and a corresponding portion of the common low-side electrode. In the example of FIG. 27 , the beam steering device does not include insulators between active cells and/or discrete high-side electrodes, but in certain embodiments the beam steering device of FIG. 27 is configured to manage fringing field losses to steering efficiency using a steering controller 2616 and/or voltage controller 2612 that are configured to reduce fringing field losses. In certain embodiments, the beam steering device of FIG. 27 is implemented with a half-wave voltage profile, for example as described in the disclosure referencing FIGS. 29-31 . In certain embodiments, one or more portions of the example beam steering device in FIG. 27 are provided with an aspect ratio that is 1 or about 1.

Referencing FIG. 28 , an example beam steering device is depicted, similar to the beam steering device depicted in FIG. 27 . The beam steering device in the example of FIG. 28 includes a discrete high-side electrode 2801 and an opposing discrete low-side electrode 2803. The beam steering device includes an EO active layer forming active cells 2608, with each active cell 2608 formed from a portion of the EO active layer between opposing electrodes 2801, 2803. In certain embodiments, one or more electrodes may omit an insulator therebetween, and/or the beam steering device of FIG. 28 may be operated in a half-wave voltage profile. In certain embodiments, for example depending upon the hardware and electrode types to implement the desired voltage profile on the electrodes, the utilization of discrete low-side electrodes 2803 may provide for a more convenient development of the voltage profile, such as by manipulating separate voltages on the low-side electrodes 2803.

In certain embodiments, for example where providing an aspect ratio of 1 or about 1 drives the design to a reduced number of electrodes per reset (e.g., due to the size of the aperture and/or beam steering device), a half-wave voltage profile may be combined with resistive electrodes, providing for some reduction in quantization losses while achieving the half-wave voltage profile advantage for fringing field losses. As will be described in the disclosure referencing FIG. 30 , a half-wave voltage profile enforces a maximum fringing field region (flyback distance) that is equal to the distance between discrete electrodes. For comparison, a castle arrangement enforces a maximum flyback distance that is a width of one discrete electrode, and a chess arrangement enforces a maximum flyback distance that is a theoretical value of zero (e.g., where each electrode is surrounded by an insulator, limiting the edge effect at the extent of the electrode). Certain further considerations include the desirability of an aspect ratio of about 1 for half-wave voltage portions of a beam steering device, the desirability of a match in optical properties between the substrate and the EO active material for a castle arrangement portion of the beam steering device, and the desirability of a match in optical properties between the insulator and the EO active material for a chess arrangement portion of the beam steering device. One of skill in the art, having the benefit of the disclosures herein, can readily determine arrangements for a beam steering device utilizing various features described herein, including: the usage of insulators; a chess arrangement; a castle arrangement; selected aspect ratios; a selected voltage progression including a half-wave voltage profile; selected optical properties for the EO active layer, the substrate, and/or the insulator(s); and/or the utilization of a reflective layer. Certain considerations in determining which features are utilized for a particular beam steering device include, without limitation to any other aspect of the present disclosure: the desired device steering capability; steering efficiency; voltages provided and the control thereof; manufacturing considerations; and/or the desired size of the beam steering device.

Referencing FIG. 29 , an example steering controller 2616 and voltage controller 2612 are configured to reduce fringing field losses in a beam steering device, including a beam steering device with or without insulating elements. The example steering controller 2616 includes a steering request circuit 2006 that determines steering value(s) 2012, for example steering directions, target locations, steering efficiency values, or the like. In certain embodiments, the steering value(s) 2012 include selected wavelengths or frequencies of incident EM radiation, selected polarities, selected steering axes, or other parameters. The example steering controller 2616 further includes a steering configuration circuit 1908 that determines EO command value(s) 1910, which may include desired optical characteristics (e.g., OPD changes) throughout the beam steering device that are responsive to the steering request value(s) 2012. In certain embodiments, the EO command value(s) 1910 are determined for one or more various layers in the beam steering device, for example layers that are responsive to selected wavelengths, polarities, efficiencies, axes of steering, etc. In certain embodiments, the steering configuration circuit 1908 utilizes a half-wave voltage profile 2908 to determine the EO command value(s) 1910, which may be utilized for one or more EO active layers in the beam steering device, and/or portions of one or more EO active layers. It can be seen that, in certain embodiments, one or more layers of a beam steering device may utilize a half-wave voltage profile 2908, while other layers of the beam steering device may be configured to utilize another voltage profile. The example steering controller 2616 further includes a steering implementation circuit 1914 that provides commands to the voltage controller 2612 responsive to the EO command value(s) 1910. In certain embodiments, the translation between the EO command value(s) 1910 and selected voltages for various active cells throughout the beam steering device may be performed by the steering implementation circuit 1914 (e.g., passing voltage commands directly to the voltage controller 2612), or by the voltage controller 2612 (e.g., translating EO command value(s) 1910 into voltage value(s) 2010 for electrodes in the beam steering device). The example voltage controller 2612 provides the voltage value(s) 2010 to electrodes (high-side electrodes, or both high-side and low-side electrodes), either by operating voltage control hardware (e.g., solid state switches, PWM devices, relays, or the like) directly, or by providing voltage value(s) 2010 to a hardware layer that is responsive to the voltage value(s) 2010 thereby energizing the electrodes in a manner that implements the EO command value(s) 1910 in active cells of the beam steering device.

FIG. 30 is an example depiction of a realistic phase profile 2808 which, according to modeling and calculations, it is believed to be achievable using various aspects of the present disclosure, including a steering controller 2616 and voltage controller 2612 such as depicted in FIG. 29 , and/or using a procedure such as that depicted in FIG. 31 . In the example of FIG. 30 , the OPD progression 2806 is depicted as being above and below a nominal voltage 2804, with a positive and negative voltage relative to the nominal voltage, and may be referenced as a half-wave voltage profile. Additionally, in the example of FIG. 30 , the aspect ratio is provided with a value of about 1. In the example of FIG. 30 , the reset occurs between a positive voltage electrode and a negative voltage electrode. It has been found that a voltage profile such as that depicted in FIG. 30 , combined with an aspect ratio of about 1, provides for a rapid reset of the voltage with fringing field region limited to the distance between electrodes even without the utilization of insulators, providing a significant decrease in fringing field losses at the reset. The example of FIG. 30 depicts resistive electrodes, although conductive electrodes may also be utilized. Because the maximum voltage in the EO active layer is one-half of the voltage in a nominal voltage phase delay profile (e.g., reset from a 2π delay voltage to a zero delay voltage), the thickness of the EO active layer using a half-wave voltage profile can be one-half of the thickness utilized for a nominal voltage phase delay profile. Additionally, the addition of a reflective layer (e.g., a reflective substrate, reflective ground electrode, or a dedicated reflective layer) can provide for a thickness of one-fourth the thickness utilized for a nominal voltage phase delay profile.

In certain embodiments, the utilization of an ultra-thin EO active layer (e.g., ¼λ which may be 500 nm or less for certain steered wavelengths) provides for additional capabilities. For example, the small physical footprint and ease of manufacture provides for the ready addition of extra layers to steer additional wavelengths, incremental steering capability, and/or steering of additional polarities and/or axes of steering. In another example, the ultra-thin layer provides for increased energy throughput capability, as the thin layer absorbs a lower fraction of energy flow-through as heat, and has a more favorable heat rejection environment (lower capacity, and a shorter heat conduction path) that is amenable to an active or passive cooling system (e.g., a cooling layer in thermal contact with the reflective layer).

In the example of FIG. 30 , the high voltage 2802 of the phase delay progression may be consistent with a π phase delay, and the low voltage 2806 may be consistent with a -π phase delay, such that at the reset position 108 a 2π (or 2πn) reset is applied, but the total voltage in the system is relative to the nominal voltage 2804. Accordingly, it can be seen that the greatest magnitude of phase delay (and corresponding voltage) that is enforced by any active cell in the example of FIG. 30 is π (either +/- π), and accordingly a greatest thickness required for an active cell can be as low as one-half λ, instead of λ, which is generally required when a magnitude 2π phase delay is applied within a single active cell.

The example of FIG. 30 depicts a symmetrical voltage profile (e.g., the high voltage value 2802 and the low voltage value 2806 are both the same distance from the nominal voltage value 2804), although the voltage profile may not be symmetrical. Additionally, a half-wave voltage profile may nevertheless be utilized with a greatest magnitude phase delay that exceeds +/- π, which may be symmetrical.

Referencing FIG. 31 , an example procedure 3100 to steer an incident EM beam using a half-wave voltage profile is schematically depicted. The procedure 3100 includes an operation 2102 to receive an incident EM beam, and an operation 3104 to determine a steering request value for the incident EM beam. The example procedure 3100 further includes an operation 3106 to determine a half-wave voltage profile that is responsive to the steering request value - for example to provide an OPD profile on an EO active layer of a beam steering device that is responsive to the steering request value and the incident EM beam. The example procedure 3100 further includes an operation 3108 to provide voltage commands in response to the half-wave voltage profile, thereby configuring an EO active layer and steering the incident EM beam. The example operation 3108 includes providing a voltage progression across the EO active layer, and providing reset positions where the power of a last electrode (or capacitor) of a first delay stage is approximately equal and of opposite sign as the power of a first electrode (or capacitor) of a second delay stage. An example operation 3108 includes providing voltages such that the last electrode of the first delay stage has an approximately equal positive voltage compared to a negative voltage of the first electrode of the second delay stage.

Referencing FIG. 32 , an example beam steering device is depicted including a thin beam steering device 3206. The example thin beam steering device 3206 may be any modulo 2π phase shifting device, including a number of active cells with voltage resets, as described throughout the present disclosure, for example in FIGS. 5-31 , and/or FIG. 44 , and the related descriptions. In certain embodiments, the thin beam steering device 3206 may be in a castle configuration, a castle pro configuration, a chess configuration, a chess pro configuration, and/or an alternating resistor-electrode configuration. In certain embodiments, the thin beam steering device 3206 may include one or more layers of thin beam steering devices. The example of FIG. 32 additionally includes a convex lens portion 3202 and a concave lens portion 3204. In certain embodiments, an incident EM beam enters the beam steering device at the convex lens portion 3202, traverses through the thin beam steering device 3206, and is emitted from the surface of the concave lens portion 3204. In certain embodiments, the embodiment of FIG. 32 is referenced as a zero-power meniscus lens embodiment, as the lens portions 3202, 3204 are operative with an unpowered lens. The convex lens portion 3202 converges the steered EM beam, and the concave lens portion 3204 amplifies the steering of the EM beam, while diverging the steered EM beam (offset by the convergence of the convex portion). While the embodiment of FIG. 32 may utilize an unpowered lens, in certain embodiments one or more of the lens portions utilized may alternatively (or additionally) include a powered lens, such as a varifocal lens (e.g., reference US PCT application PCT/US19/57616 at FIGS. 54-56 and the related descriptions). Based on calculations and modeling, it is believed that a beam steering device such as that depicted in FIGS. 32 and 33 is capable to steer an incident EM beam to an angle exceeding +/- 20°, and/or exceeding +/- 30°.

Referencing FIG. 33 , another embodiment of a beam steering device is depicted, with separated components for the convex lens portion 3302 and the concave lens portion 3304. In certain embodiments, the separation of the lens portions 3302, 3304 may provide for ease of fabrication, ease of cooling and/or electrical connections to the thin beam steering device 3206, and/or separation of the lens portions 3302, 3304 as distinct devices and/or having distinct operating configurations. In certain embodiments, for example where the lens portions 3302, 3304 are an integrated component (e.g., as in FIG. 32 ) and/or manufactured by the same processes, aberrations in the lens portions may acceptably offset. In certain embodiments, manufacturing tolerances may be utilized to ensure acceptable performance of the lens portions 3302, 3304.

Referencing FIG. 34 , an example system 3400 of the present disclosure is depicted. The example system 3400 includes a beam steering device having a wide angle capability and preserving steering efficiency using a number of aspects of the present disclosure. The specific implementation of FIG. 3400 is provided for illustration, and the components of the example are not limiting to the present disclosure. The example system 3400 includes an incident beam 3412 to be steered to a selected location (e.g., a target area, a sweep area during a scan, etc.). The example beam steering device 3400 may additionally or alternatively direct the optical path to a target location, observed location, etc., to receive the EM beam 3412 at a detection array, photonic array, sensor, etc. (e.g., steering a received EM beam from a target location to a detector, rather than steering from an EM source to the target location, and/or a combination of these – for example steering an EM beam from an EM source to the target location, and receiving returns from the target location that are steered to a detector). The example system 3400 includes an initial steering layer 3402, which is capable to steer the EM beam 3412 to a selected angle. An example initial steering layer 3402 includes a PBG, but may additionally or alternatively be any steering device, such as a thin beam steering device, a bulk beam steering device, a discrete steering device (e.g., capable to steer between a number of discrete steering angles), and/or a continuous steering device (e.g., capable to steer at a selected angle within a capability range of the steering device, an arbitrary angle, and/or a high number of discrete angles sufficient to be considered “continuous” for the application and/or purpose of the system 3400).

An example initial steering layer 3402 includes a polar birefringence grating, a birefringement prism, or the like. In the example where initial steering layer 3402 is a PBG, the example system 3400 includes the PBG 3402 steering the incident beam 3412 to an offset angle, which is selectable based on the polarization of the incident beam 3412. The example system 100 further includes a first volume hologram 3404 and a second volume hologram 3406. The volume holograms 3404, 3406 adjust the angle (e.g., steer) of the incident EM beam 3412 for light received at a specific angle (e.g., the upper beam 3414 received at the first volume hologram 3404, or the lower beam 3416 received at the second volume hologram 3406), and pass through light received at another angle (e.g., the upper beam 3414 received at the second volume hologram 3406, or the lower beam 3416 received at the first volume hologram 3404). The example system 3400 includes a thin beam steering device 3410, which provides for continuous steering of the final emitted beam (e.g., 3414 or 3416). The final steering device 3410 may be a discrete steering device, continuous steering device, thin beam steering device, and/or bulk beam steering device. Examples herein describe the final steering device 3410 for clarity of the description. In certain embodiments, a thin beam steering device 3410 provides certain advantages that may be useful depending upon the particular system and application, for example providing for a small axial span of the overall system 3400 to accommodate the final steering device 3410, and an enhanced incidence area allowing for a wide range of steering capability that still impinges on the active steering portion of the thin beam steering device 3410.

It can be seen that the thin beam steering device 3410 steers relative to the incident angle into the thin beam steering device 3410, and is approximately additive to the available angles of the incident light. For example, if the initial steering layer 3402 and volume hologram(s) 3404, 3406 combination is capable to +/-20 degrees (e.g., 20 degrees “up” or “left” for the upper path 3414, and 20 degrees “down” or “right” for the lower path 3416), then a thin beam steering device 3410 capable of steering to +/- 20 degrees results in a beam steering device 3400 capable to steer to +/- 40 degrees. The example of FIG. 34 depicts steering in a given axis (e.g., elevation, azimuth, or other selected axis). It can be seen that additional steering layers (e.g., initial steering layer(s) 3402, volume holograms 3404, 3406, thin and/or bulk steering devices 3410, etc.) can be provided to steer in additional axes. In certain embodiments, inclusion of polarization management, etc., may be provided between steering layers according to the response of devices in the layers (e.g., PBGs, volume holograms, etc.) to the polarization of the incident beam 3412 as it progresses through the system 3400.

The specific example of FIG. 34 provides for a number of benefits. For example, the utilization of a PBG 3402 provides for a convenient application of a selected steering angle, for example utilized by the volume hologram(s) 3404, 3406, and efficient discrete steering by the volume holograms 3404, 3406 to an extended angle, providing for an enhancement to the baseline steering capability of the system 3400 as emitted by the thin beam steering device 3410. Embodiments of the example of FIG. 34 can readily be constructed to provide for a capability of +/- 60 degrees of steering, with an overall steering efficiency of over 90%. It will be noted that the geometric efficiency (or “cosine efficiency”) at 60 degree steering, with a flat emission surface (e.g., the right hand face of the thin beam steering device 3410 in the depiction of FIG. 1 ) will be 0.5 (or COS 60°), which is a physical constraint on any beam steering device. The geometric efficiency can be increased with the utilization of a curved emission surface, for example as set forth in embodiments of the present disclosure utilizing a fishtail booster (or meniscus lens), such as set forth in FIG. 32 and the related disclosure.

It will be understood that the phase delay progression profile across the continuous steering element 3410 will be adjusted to account for the incident angle of light (e.g., from the left side in FIG. 34 ) to achieve the desired steering angle and optical characteristics. For example, the phase wave front of the incident beam 3412 is not perpendicular to the thin beam steering device 3410 when the prior steering elements 3402, 3404, 3406 are active. Accordingly, the phase delay progression (e.g., reference FIGS. 6, 8, 30, and 46 ) may be adjusted to provide a selected steering, phase profile, and the like for the emitted beam 3414, 3416, and/or to configure received EM radiation (e.g., compensating for the steering elements 3402, 3404, 3406 (e.g., which are downstream rather than upstream steering elements for received EM radiation) back into an EM detector receiving EM radiation 3412 - not shown).

Certain additional and/or optional features of FIG. 34 are described following, which are not limiting to the embodiments contemplated in the present disclosure. An example system includes a continuous steering device (e.g., a thin beam steering device, a bulk steering device, etc.), either at the position of the initial steering layer 3402, and/or replacing all or a portion of the initial steering layer 3402, first volume hologram 3404, and/or second volume hologram 3406. Additionally or alternatively, additional stages of volume holograms 3404, 3406 may be provided, for example to steer in additional directions, to provide additional discrete steering before the continuous steering element 3410, etc. In certain embodiments, one or more discrete steering elements 3402, 3404, 3406 may be provided downstream of the continuous steering element 3410.

Referencing FIGS. 35-37 , example steering operations of a continuous steering element 3410 and/or steering system 3400 are depicted. The example steering operations depicted in FIGS. 35-37 are example illustrative steering data, which is representative of continuous steering elements 3410 according to the thin and/or bulk steering devices of the present disclosure. The steering capabilities depicted in FIGS. 35-37 cooperate with offset steering provided by other steering elements (e.g., 3402, 3404, 3406) set forth herein. Example and non-limiting continuous steering elements 3410 are capable to steer to an angle exceeding 20 degrees while maintaining > 90% efficiency (e.g., 20 degrees at 92.3% efficiency in the example of FIG. 37 ). The depicted performance of FIGS. 35-37 is achievable at least by a thin beam steering device utilizing a half-wave voltage profile.

Referencing FIG. 38 , an example thin beam steering device 110 is depicted with an associated fishtail booster 3802 (and/or meniscus lens). In certain embodiments, the fishtail booster 3802 is provided with zero power – or the fishtail booster 3802 preserves the convergence/divergence character of the incident beam 3412. The incident beam 3412 is depicted as normal to the thin beam steering device 3410 for clarity of the present description, but it will be understood that the incident beam 3412 may be steered at some angle (e.g., as depicted in FIG. 34 ). The fishtail booster 3802 extends the steering capability of the thin beam steering device 3410. For example, a thin beam steering device 3410 according to embodiments of the present disclosure, such as a thin beam steering device 3410 utilizing a half-wave voltage profile, can achieve steering of about 30 degrees (reference FIG. 40 ), at high efficiency. An example thin beam steering device 3410 with an associated fishtail booster 3802 can steer to about 20 degrees (device 3410 capability), boosted to about 28.5 degrees without a loss of steering efficiency. In certain embodiments, the fishtail booster 3802 can also modestly reduce cosine losses, for example decreasing the geometric angle between the emission surface and the steered light beam 3414. The power (e.g., convergence/divergence characteristic) of the fishtail booster 3802 can be manipulated using the thickness of the lens portions, the radius of curvature of the lens portions, and/or the index of refraction of the lens material for the meniscus lens. In certain embodiments, the front portion (e.g., on the incident beam 3412 side), the rear portion (e.g., on the emitted beam 3414 side), or both, may be implemented as a varifocal lens (VFL). The lens action may be provided with an integrated lens body (e.g., as depicted in FIGS. 32, 38, and 39 ), with lens portions provided on each side of the thin beam steering device 3410 (e.g., as depicted in FIG. 33 ), and/or utilizing a VFL for one or both lens portions. Any of these arrangements may be referenced as a fishtail booster 3802 and/or meniscus lens herein. An example thin beam steering device 3410 with a fishtail booster 3802 includes potassium tantalate niobite (KTN) as an active material (or EO material) for the thin beam steering device, and is capable of deflection (steering) of up to +/-15-25 degrees from the thin beam steering device, with up to +/-30 degrees utilizing the fishtail booster 3802 portion for a steered beam having a wavelength of 1550 nm. It can be seen that a final steering capability of +/-30 degrees provides up to +/-60 degrees total steering for a system 3400 with complete coverage, utilizing up to +/-30 degrees of pre-steering (whether discrete or continuous). In certain embodiments, for example where the incident beam 3412 can be provided in a normal orientation to the thin beam steering device 3410, coverage for the middle steering region can be performed by the thin beam steering device 3410 steering unassisted, and the available steering range can be extended further. An example embodiment includes the thin beam steering device 3410 (possibly with an associated fishtail booster 3802) capable to steer to +/-30 degrees, with enhanced steering to each side of up to 30 degrees, providing for up to a full +/-90 degree steering coverage. Accordingly, embodiments of the present disclosure can provide full steering coverage with an arbitrary range limit of up to +/- 90 degrees, which is the theoretical limit for a flat emission surface. It will be understood that cosine losses increase significantly at high steering angles, for example cosine losses are 50% at 60 degrees, and 100% at 90 degrees, so very high steering capability may be unnecessary for many applications. Embodiments herein are, therefore, capable to support any application where beam steering is desired from a flat emission surface, with the only limit being the cosine losses that remain acceptable for the given application.

Referencing FIG. 39 , an example beam steering system 3900 includes a number of steering layers, and a thin beam steering device 3410 with an associated fishtail booster 3802. The example beam steering system 3900 includes a first steering layer 3902 that selectively steers an incident beam 3412 in a first or second direction (e.g., the first direction steering to emitted beam 3414, and the second direction steering to emitted beam 3416). The first steering layer 3902 may be a discrete steering element (e.g., a PBG) or a continuous steering element (e.g., a bulk steering device, thin steering device, etc.). The example beam steering system 3900 includes a first volume hologram 3904 responsive to a first incident angle to increase the steering angle further before progression to the thin beam steering device 3410, and a second volume hologram 3906 responsive to a second incident angle to increase the steering angle further before progression to the thin beam steering device 3410. It will be seen that the volume holograms 3904, 3906 may be utilized as discrete steering angle enhancers, to extend the steering range of the thin beam steering device 3410. In certain embodiments, the incident beam 3412 may be provided without steering from the first steering layer 3902 — for example where the native steering capability of the thin beam steering device 3410 under current operating conditions is capable to steer to a steering target value. In certain embodiments, for example where the first steering layer 3902 is a continuous steering element, the incident beam 3412 may be steered to an angle that is not one of the coded angles for the volume holograms 3904, 3906, wherein the incident beam 3412 will pass through the volume holograms 3904, 3906 without steering angle enhancement from the volume holograms 3904, 3906, for example to provide a minor steering enhancement from the first steering layer 3902 to the thin beam steering device 3410. The example of FIG. 39 includes an optional fishtail booster 3802 depicted in an example configuration. The steering performed by the first steering layer 3902 may be controlled by manipulation of the polarization of the incident beam 3412, the control of phase delay progression in the first steering layer 3902 (e.g., controlling a voltage profile of a steering device, which may be a thin beam steering device and/or a bulk beam steering device), or the like. In certain embodiments, the volume holograms 3904, 3906 may be omitted entirely, for example where the first steering layer 3902 is capable to provide sufficient steering enhancement for the steering window of the application without the discrete enhancement provided by the volume hologram(s) 3904, 3906. The example of FIG. 39 depicts steering in a given axis, but may be adjusted, as set forth throughout the present disclosure, to also provide steering in a second axis. Where two axis steering is provided, and for embodiments throughout the present disclosure, the steering layers utilized for each steering axis may be distinct (e.g., a different set and/or sequence of steering elements for each), and/or the steering capability for each steering axis may be distinct.

An example thin film scanner (e.g., of a thin beam steering device 3410) acts as a variable blazed grating. Generally, the relation between the incident angle and diffractive angle (e.g., the trace of 3414/3416 going into, and leaving, the thin beam steering device 3410) can be approximated in Equation 6:

k_(i)sinθ_(i) ± qK = k_(d)sinθ^(′)_(d)

Eq. 6 Relationship between incident angle and diffractive angle for a thin film scanner

In equation 6, θ_(i) is the incident angle and θ′_(d) is the deflection angle inside the grating, k_(i) = n_(i)2π/λ is the incident wavenumber, and n_(i) is the index of the medium in the incident side. n_(i) is considered to be approximately 1, because the light is assumed to enter from the air, but this parameter may be modified for other medium as will be understood to the person of skill in the art. k_(d) is defined as k_(d) = n_(d)2π/λ which is the deflection wavenumber and n_(d) is the index of the medium in the deflection side, q is the diffraction order. The K′, is the grating wavenumber which is defined as in equation 7:

K = 2π/Λ

Eq. 7 Definition of the grating wavenumber

In equation 7, Λ is the reset period.

In the case of a transmissive deflector, light will be refracted when it exits the grating material to air. According to Snell’s law (equation 8):

n_(d)sinθ^(′)_(d) = sinθ_(d)

Eq. 8 Snell’s law, determining deflection angle based on index ratios (assumed 1 for air)

In equation 8, θ_(d) is the deflection angle in the air. Therefore, the grating formula for a transmissive grating will be approximated by equation 9:

$sin\theta_{d} = sin\theta_{i} \pm q\frac{\lambda}{\Lambda}$

Eq. 9 Grating formula for a transmissive grating

The formula in Eq. 9 shows that wider deflection angles may be achieved for non-normal incident lights if the incident angle is selected correctly. For a normal (perpendicular) incident, the deflection angle will be approximated by equation 10:

$\theta_{d} = \pm \sin^{- 1}\left( {q\frac{\lambda}{\Lambda}} \right)$

Eq. 10 Deflection angle for a normal-incident EM beam

Note that, if sinθ_(d) > 1, that wave may not show up in the far-field. Therefore, for a given desired angle it has been found preferable that

$- 1 < sin\theta_{i} \pm q\frac{\lambda}{\Lambda} < 1.$

In a case of perfect blazed grating, the maximum intensity will be for q=±1. Therefore, for a normal incident, sinθ_(i) = 0, where the thin beam steering device approximates a perfect blazed grating, the deflection angle will be approximated by equation 11:

$\theta_{d} = \pm \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right)$

Eq. 11 Deflection angle estimate for a normal incident EM beam

For the largest design angle, the Λ is preferably the minimum and vice versa. For example, if a thin film is designed to deflect a 1550 nm normally incident light to ±20°, the minimum reset period (A) will be approximately 4.5 µm.

In certain embodiments, the steering device is configured such that only the orders of ±1 are survived; otherwise, the diffractive efficiency will be significantly reduced because a significant fraction of light will be sent to other angles associated with the higher orders of diffraction where |q λ/Λ| < 1.

Generally, if

$sin\theta_{i} = \pm \frac{\lambda}{\Lambda},$

the final steering angle for q=±1 can be estimated by equation 12:

$\begin{array}{l} \left. sin\theta_{d} = sin\theta_{i} \pm q\frac{\lambda}{\Lambda} = \pm \frac{\lambda}{\Lambda} \pm \frac{\lambda}{\Lambda} = \pm 2\frac{\lambda}{\Lambda}\rightarrow \right. \\ {- \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right) < \theta_{d} < \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right)} \end{array}$

Eq. 12 Deflection angle with a non-perpendicular incident EM beam

For example, for

$\theta_{i} = - \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

the smallest angle will be approximately 0°, and the widest angle will be

$- \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right).$

For

$\theta_{i} = + \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

the smallest angle will be approximately 0°, and the widest angle will be

$+ \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right).$

Therefore, by providing the incident angles of

$\theta_{i} = \pm \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

light can be steered up to

$\pm \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right).$

The parameter

$\pm \frac{\lambda}{\Lambda}$

is the sine of the maximum angle which the thin film scanner (e.g., the thin beam steering device 110, and/or with an associated fishtail booster 502) is designed for in the case of a normal incident EM beam. Thus, except in atypical cases, Λ may be the smallest reset period that the thin film scanner can offer. By using the halfwave voltage method equipped with the fishtail booster, a normally incident (sinθ_(i) = 0) light may be steered up to ±30°. If the intensity of the ±1 orders is maximized, then

$\left. \left| {sin\theta_{d}} \right| = 0.5 = \frac{\lambda}{\Lambda}\rightarrow\frac{\lambda}{\Lambda} = 0.5. \right.$

The parameter Λ is the smallest reset period available where the aspect ratio (e.g., thickness to length of active cells — see U.S. Application 16/999,815 at FIG. 26 and the related description) is still 1. In an example, if sinθ_(i) = ±0.5, the light can be steered to approximately ±90°.

In the example, where q = ±1, then

$\begin{array}{l} {sin\theta_{d} = sin\theta_{i} \pm q\frac{\lambda}{\Lambda} = sin\theta_{i} \pm \frac{\lambda}{\Lambda}} \\ \left. = \pm 0.5 + \pm 0.5 = \pm 1\rightarrow - 90{^\circ} < \theta_{d} < 90{^\circ} \cdot \right. \end{array}$

An example beam steering system utilizes a thin beam steering device 110, such as a half-wave voltage based device, without an associated fishtail booster. The example system can readily be configured for the thin beam steering device 110 portion to have unassisted efficient steering capability to ±20°. Accordingly, for such a system:

$\left. \left| {sin\theta_{d}} \right| = \left| {sin20} \right| = 0.342 = \frac{\lambda}{\Lambda}\rightarrow\frac{\lambda}{\Lambda} = 0.342, \right.$

and it follows that the final enhanced steering capability is approximately ±43° (e.g., where q=±1, then

$\begin{array}{l} {sin\theta_{d} = sin\theta_{i} \pm q\frac{\lambda}{\Lambda} = sin\theta_{i} \pm \frac{\lambda}{\Lambda} =} \\ \left. \pm 0.342 + \pm 0.342 = \pm 0.684\rightarrow - 43{^\circ} < \theta_{d} < 43{^\circ} \right. \end{array}$

).

Thus, providing enhanced steering utilizing incident angle adjustments as set forth herein, the steering capability generated for incident angle of

$\theta_{i} = - \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right)$

and

$\theta_{i} = + \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right)$

may steer to

$\pm \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right),$

with a thin film scanner designed for steering the normal incident light to

$\pm \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right).$

An example beam steering system capable to steer to ±60° is described following, and is not limiting to any other aspect of the present disclosure. The example beam steering system is consistent with the example depicted in FIG. 34 . The example beam steering device includes a thin beam steering device designed for steering the normal incident light up to ±25.6°, a PBG, and two volume holograms interposed between the PBG and the thin beam steering device. In the example, the volume holograms are configured, in coordination with the PBG, to provide a normal incident beam onto the PBG as an incident beam onto the thin beam steering device at either +25.6° or -25.6°. For example, the PBG may be configured to provide a first or second angle to the incident beam, such as in response to a polarization of the incident beam, where the first angle matches a selected angle that a first volume hologram is responsive to, and where the second angle matches a selected angle that the second volume hologram is responsive to. In certain embodiments, the PBG in the example may be replaced with a different type of steering element, such as a continuous steering element that is controllable to provide the selected angle(s) for the volume holograms. In the example, the PBG (or other leading steering element) steers the incident beam to the selected angle(s), a first volume hologram steers the light to

$+ \sin^{\text{-}1}\left( \frac{\lambda}{\Lambda} \right),$

the second volume hologram steers the light to

$\text{-}\sin^{\text{-}1}\left( \frac{\lambda}{\Lambda} \right),$

the thin beam steering device is designed to steer a normal incident beam to

$+ /{\text{- sin}^{\text{-1}}\left( \frac{\lambda}{\Lambda} \right),}$

and the overall steering capability of the beam steering system is

$+ /{\text{- sin}^{\text{-1}}\left( {2\frac{\lambda}{\Lambda}} \right).}$

As described herein, embodiments of the present disclosure include steering of an incident EM beam, where the EM beam incidence to a final steering layer (e.g., a thin beam steering device) is not a normal incidence angle during at least certain operating conditions. Accordingly, in certain embodiments, consideration in the arrangement of a beam steering system to first order reflection due to high incidence angles may be considered, and may be considered as a loss in steering efficiency. Referencing FIG. 41 , an illustrative operating diagram for a given beam steering device. It can be seen in the example of FIG. 41 that low, and typically insignificant, reflection occurs up to about θ_(i) 18 degrees. In the example of FIG. 41 , an incidence angle of even 30 degrees, sufficient to support many arrangements that can provide +/-60 degree steering, results in about 5% reflection loss. In many applications, a 5% reflection loss may be readily acceptable given the capability of a +/-60 degree, diffraction-efficient, beam steering device of the present disclosure, relative to the steering efficiency and capability of previously known devices. The example of FIG. 41 is determined for a typical scanner material and EM beam profile (e.g., wavelength, intensity, etc.). The type of data depicted in FIG. 41 is readily available to one of skill in the art, having the benefit of the present disclosure, and information ordinarily available when contemplating a particular system, such as scanner materials, EM beam characteristics, surface conditions (e.g., availability and/or utilization of anti-reflective coatings, surface characteristics, etc.). It can be seen that reflection losses for the illustrative data in FIG. 41 do not reach 10% until θ_(i) is about 60 degrees. The present disclosure is not limiting to particular θ_(i) values, including values exceeding 60 degrees, but it is noted that a given beam steering device can be arbitrarily capable (e.g., steering up to +/-90 degrees) with a θ_(i) value significantly lower than 60 degrees. Accordingly, the present disclosure sets forth beam steering systems that can steer to arbitrary capability with steering efficiencies that remain high for a broad range of applications. In certain embodiments, losses for reflection occurring at high values of θ_(i) may nevertheless be acceptable, for example where the high value of θ_(i) provides benefits for a given system that exceed the reflection loss for a contemplated application, such as reduced capability requirements for a thin beam steering device 3410, elimination of other components (e.g., a fishtail booster 3802), transfer of some steering duty to a high efficiency component (e.g., a volumetric hologram), manipulation of heat generation and/or expulsion between selected locations and/or components within the beam steering device, or the like.

A few design considerations for a volume hologram are described following, which are illustrative and not limiting. An example volume hologram steers the incident EM beam to an angle such as

$- \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right)\mspace{6mu}\text{or}\mspace{6mu}\text{+}\mspace{6mu}\text{sin}^{- 1}\left( \frac{\lambda}{\Lambda} \right).$

The example volume hologram acts like a diffraction grating having a thickness, and is made of a recording medium (e.g., photo-thermal glass) extending between planes of z=0 (e.g., one side of the volume hologram active medium) and z=Δ (e.g., the opposing side of the volume hologram active medium). Equation 13 sets forth the interference pattern of the volume hologram in x, y, and z coordinates:

$I\left( {x,y,z} \right) = \left| {\sqrt{I_{r}}e^{- ik_{r \cdot}r} + \sqrt{I_{o}}e^{- ik_{o \cdot}r}} \right|^{2} = I_{r} + I_{o} + 2\sqrt{I_{r}I_{o}}\cos\left( {k_{g \cdot}r} \right)$

Eq. 13 Interference pattern of an example volume hologram

In the example of equation 13, I_(r) and I_(o) are the intensities of the reference and object beams and k_(r) and k_(o) are the object and reference wavevector, respectively. In the example, the grating vector k_(g) = k_(o) - k_(r), and the sinusoidal pattern of the period is =2π/|k_(g)|. If the angle between the reference wave points and the object wave is O, the grating period is |kg| = 2ksinΘ/2 and the period will be approximately

$\text{L} = \frac{\lambda}{{2sin\Theta}/2}.$

In the example, parallel plates are recorded and form a thick diffraction grating which is called the volume hologram. When the volume hologram is illuminated with a wave, the parallel planes of the grating reflect the wave only when the Bragg condition of

$\sin\varphi = \frac{\lambda}{2L}$

is satisfied; otherwise, the light will be transmitted.

The angle of φ is the angle between the planes of grating and the incident reference wave, which is approximately half of the angle between the reference and object waves. For an example volume hologram providing an incident angle of

$\theta_{i} = - \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

and a second example volume hologram to provide

$\theta_{i} = + \sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

then the angle between the incident light and the parallel planes of the grating in the first and second volume hologram is preferably

$\varphi = - 0.5\sin^{- 1}\left( \frac{\lambda}{\Lambda} \right)\mspace{6mu}\text{and}\mspace{6mu}\varphi = 0.5\sin^{- 1}\left( \frac{\lambda}{\Lambda} \right),$

respectively, to satisfy the Bragg condition.

Table 3 summarizes example arrangements to steer light to selected wide angles as described. The achievable angle capability for a steering scanner arrangement may be limited by the total internal reflection angle of the second steering layer (e.g., a thin beam scanning device, continuous steering device, etc.), which will limit the impingement angle on the second steering layer which can be utilized to boost steering capability. Example embodiments may utilize a PBG and/or volume holograms (VH) to provide for initial steering before the second steering layer, but initial steering may be provided alternatively or additionally by any other steering element, such as a continuous or discrete steering device, a thin beam steering device of any type, and/or a steering device combined with one or more VHs.

TABLE 3 Example arrangements of a beam steering system to steer to selected angles Steering target range: Steering to $\pm \sin^{- 1}\left( {2\frac{\lambda}{\Lambda}} \right)$ (limited to the total internal reflection angle) Steering to ±90° (Limiting embodiment that is not fully achievable due to total internal reflection limit and cosine loss) Steering to ±60° Steering to ±40° Type of scanner Any applicable type. The angle should not be very wide otherwise the total internal reflection may happen Alternating resistor scanner, chess scanner, and/or scanner utilizing a half-wave voltage profile and/or fishtail booster. The example system is located after a PBG and two VHs, or any other type of discrete or continuous steering layer. Alternating resistor scanner, chess scanner, and/or scanner utilizing a half-wave voltage profile and/or fishtail booster. The example system is located after a PBG and two VHs, or any other type of discrete or continuous steering layer. Alternating resistor scanner, chess scanner, and/or scanner utilizing a half-wave voltage profile. The example system is located after a PBG and two VHs, or any other type of discrete or continuous steering layer. This steering capability is achievable without a fishtail booster, but a fishtail booster may be utilized with other elements to provide capability margin and/or utilize other less capable components. The maximum deflection angle of the scanner for normal incident $\pm \sin^{- 1}(\frac{\lambda}{\Lambda})$ ±30° ±25.6° ±20° The Bragg condition of the volume hologram * (see the footnote) $\sin\text{(0}\text{.5sin}^{- 1}(\frac{\lambda}{\Lambda})) = \frac{\lambda}{2L}$ ${Sin}(15) = 0.2588 = \frac{\lambda}{2L}$ $0.22 = \frac{\lambda}{2L}$ $0.173 = \frac{\lambda}{2L}$ VH1′s outlet angle*(see the footnote) $+ \sin^{- 1}(\frac{\lambda}{\Lambda})$ 30° 25.6° 20° The angle between the grating and coming wave in VH1* (see the footnote) $0.5\sin^{- 1}(\frac{\lambda}{\Lambda})$ 15° 12.8° 10° VH2′s outlet angle*(see the footnote) $- \sin^{- 1}(\frac{\lambda}{\Lambda})$ -30° -25.6° -20° The angle between the grating and coming wave in VH2*(see the footnote) $- 0.5\sin^{- 1}(\frac{\lambda}{\Lambda})$ -15° -12.8° -10°

Referencing FIG. 42 , an example steering controller 4202 structured to perform certain operations for steering an EM beam, whether transmitted or received, is schematically depicted. The steering controller 4202 is depicted as a single device for clarity of description, although aspects of the steering controller 4202 may be distributed across multiple devices, implemented in hardware and/or as instructions stored on a computer readable medium, as sensors and/or actuators present in a system including the steering controller 4202, and/or through network communications and/or remote processing capabilities.

An example steering controller 4202 includes a number of circuits structured to functionally execute certain operations of the steering controller 4202. Certain operations are described in reference to FIG. 42 , but any operations, procedures, or techniques throughout the present disclosure may be implemented by, or performed by, a controller such as steering controller 4202. The example steering controller 4202 may form a part of any systems, apparatuses, devices, or other embodiments disclosed throughout the present disclosure. Without limitation to any other aspect of the present disclosure, a steering controller 4202 including one or more aspects such as those described in reference to FIG. 42 may be present in a system having one or more controllable devices such as, without limitation, a continuous steering element (e.g., a thin beam steering device and/or a bulk beam steering device), a PBG (e.g., combined with an EM source capable to provide selectable polarization), and/or a volume hologram (e.g., controlling an upstream device providing an incident beam to the volume hologram at a selected incident angle, including an angle selected to activate and/or bypass active steering of the volume hologram).

An example steering controller 4202 includes a steering request circuit 4204 that interprets a steering request value 4206 (e.g., directing a transmitted beam to a selected location, and/or at a selected angle or angles; and/or directing received EM radiation from a selected location, and/or at a selected angle or angles, to an EM receiving device such as a detector array, sensor, photonic array, optical device, etc.). The example steering controller 4202 further includes a steering configuration circuit 4208 that determines a number of electro-optical command values 4210 (e.g., values for an active layer of thin beam steering device, and/or for electrodes of a bulk steering device, thereby configuring steering operations of the steering device, a phase delay progression, and/or compensating optical characteristics to account for an incident angle θ_(i) of EM radiation on the steering device, where the EM radiation is to be steered). An example system including the steering controller 4202 includes a continuous steering element (e.g., a thin beam steering device and/or a bulk steering device) that is responsive to the number of EO command values 4210 to provide selected steering operations (e.g., utilizing a corresponding phase delay progression across the continuous steering element). An example steering controller 4202 further includes where the steering configuration circuit 4208 determines a polarization orientation 4212 (e.g., providing an EM source for the incident beam that will steer from a PBG in a selected direction) in response to the steering request value 4206 (e.g., utilizing steering regimes associated with steering targets, etc.). An example system including the steering controller 4202 includes a selectively polarized electromagnetic source (not shown) that provides the incident beam to the PBG at a selected one of a first polarization corresponding to the first angle, or a second polarization corresponding to the second angle, and where the selectively polarized electromagnetic source is responsive to the polarization orientation 4212.

Referencing FIG. 43 , an example procedure 4300 for steering an EM beam to a wide angle (e.g., > +/-30 degrees, >+/-45 degrees, up to +/-60 degrees, and/or to an arbitrary angle up to +/-90 degrees, and/or sufficiently away from 90 degrees that, depending upon the application, cosine losses for the steered beam are within acceptable parameters) is schematically depicted. The example procedure 4300 includes an operation 4302 to direct an incident electromagnetic (EM) beam to a selected one of a first selected angle or a second selected angle (e.g., utilizing a continuous steering element, and/or a PBG responsive to a polarization of the incident EM beam), and an operation 4304 to increase the selected one of the first selected angle or the second selected angle with a volume hologram responsive to the selected one of the first selected angle or the second selected angle. The example procedure 4300 further includes an operation 4306 to steer the incident EM beam to a final steering angle with a continuous steering element (e.g., a thin beam steering device and/or a bulk beam steering device.

Referencing FIG. 44 , an example procedure 4400 for steering an EM beam to a wide angle is schematically depicted. The example procedure 4400 includes an operation 4402 to adjust an incident angle, of an EM beam to be steered, impinging on a final steering device (e.g., a continuous steering element, thin beam steering device, and/or bulk beam steering device). Example operations 4402 include one or more of, without limitation: adjusting an emission angle of a PBG (e.g., PBG emitting to a volume hologram, and/or directly to the final steering device); adjusting an emission angle of an initial steering device (e.g., a continuous steering element, thin beam steering device, and/or bulk beam steering device, where the initial steering device emits to a volume hologram and/or directly to the final steering device); and/or enhancing an angle of an intermediate beam to form the beam impinging on the final steering device (e.g., utilizing a volume hologram to increase a steered angle of the intermediate beam before impingement on the final steering device). The example procedure 4400 further includes an operation 4404 to operate the final steering device to steer the EM beam according to a steering target value (e.g., commanding a continuous steering element, such as a thin beam steering device, bulk beam steering device, and/or a steering device associated with a fishtail booster). The example operation 4402 may include selecting an angle for impingement of the EM beam on the second steering layer (e.g., the continuous steering element), and steering the EM beam with the first steering layer (e.g., a discrete or a continuous steering element) to impinge on the second steering layer at the selected angle. The initial impingement angle on the second steering layer is limited by the total internal reflection angle of the second steering layer — for example the angle at which the incident EM beam will be rejected by the optical material of the second steering layer, and result in minimal steering efficiency for the scanner 4500.

Referencing FIG. 45 , an example thin beam scanner 4500 is depicted having a high-side electrode layer on a first side of an EO layer 10, and a low-side electrode layer 40 on a second side of the EO layer 10. The low-side electrode layer may be a continuous low-side electrode layer (e.g., as depicted), a discrete low-side electrode layer, or a combination of these.

The high-side electrode layer in the example scanner 4500 is formed from high-side electrodes 30 alternating with resistors 4502. The alternating resistor embodiment of the high-side electrode layer provides for a linear phase delay progression along the EO layer 10, improving the steering efficiency, reducing losses of the steered EM beam, and improving the quality of the transmitted steered beam as a better matching representation of the EM source beam (and/or the received EM beam). For example, referencing FIG. 46 , an illustrative phase delay progression profile 4600 of a scanner 4500 utilizing an alternating resistor arrangement is depicted. The example phase delay progression profile 4600 includes a number of linear rising portions 4602 – corresponding to the phase delay progression within the EO layer 10 associated with the resistors, and a number of flattened portions 4604 - corresponding to the phase delay progression within the EO layer 10 associated with the electrodes 30. The linearization of the resistors 4502 impinges into the portion of the EO layer 10 associated with the electrodes 30, such that the width of the flattened portions 4604 will be smaller than the width of the electrodes 30, improving the overall fit of the wavefront relative to the original wavefront before steering. The example of FIG. 46 depicts reset portions 4606, for example as utilized in a modulo 2πn steering device, which the scanner 4500 may be operated as. In certain embodiments, the scanner 4500 may be operated as a half-wave voltage profile device – for example with negative and positive voltage portions that reduce the magnitude of the maximum voltage in the scanner 4500 during steering operations. The example half-wave voltage profile description is non-limiting, and any half-wave voltage profile as set forth herein, and/or any modulo 2πn or modulo πn configuration as set forth herein may be utilized.

In certain embodiments, the thin beam scanner 4500 may include a reflective layer, for example a layer coupled to the low-side electrode layer, and/or one of the electrode layers 30, 40 included as a reflective layer. In certain embodiments, the scanner 4500 may be utilized as a thin beam scanner according to any other embodiments set forth throughout the present disclosure. Without limitation to any other aspect of the present disclosure, scanner 4500 may be utilized with a fishtail booster (e.g., reference FIGS. 32, 33, 38, 39 and the related descriptions); as a first steering layer to adjust an impingement angle on a second steering layer and/or to provide a selected angle to a volume hologram to boost the selected angle (e.g., reference FIGS. 34, 39 and the related descriptions); as a second steering layer to provide final steering to a steered EM beam (e.g., reference FIGS. 34, 39 and the related descriptions); and/or combinations of these.

In certain embodiments, the thin beam scanner 4500 may be utilized in any system, apparatus, steering device, and/or scanner as set forth herein, including any embodiment utilizing a discrete steering device, a continuous steering device, and/or a thin beam steering device. In certain embodiments, the thin beam scanner 4500 may be utilized in any processes or operations herein, and/or may include, be operatively coupled with, and/or be responsive to any controller, circuit, processor, control device, or the like as set forth herein.

Referencing FIG. 47 , an illustrative depiction of a far field pattern for a scanner 4500 consistent with the embodiment depicted in 45 is shown. The example of FIG. 47 is illustrative, and based upon simulation and experience depicts a typical capability of +/-30 degrees (e.g., steering capability to a total of 60 degrees in a selected steering axis) for an EM beam having a 1.06 µm wavelength.

The methods and systems described herein may be deployed in part or in whole through a machine having a computer, computing device, processor, circuit, and/or server that executes computer readable instructions, program codes, instructions, and/or includes hardware configured to functionally execute one or more operations of the methods and systems herein. The terms computer, computing device, processor, circuit, and/or server, (“computing device”) as utilized herein, should be understood broadly.

An example computing device includes a computer of any type, capable to access instructions stored in communication thereto such as upon a non-transient computer readable medium, whereupon the computer performs operations of the computing device upon executing the instructions. In certain embodiments, such instructions themselves comprise a computing device. Additionally or alternatively, a computing device may be a separate hardware device, one or more computing resources distributed across hardware devices, and/or may include such aspects as logical circuits, embedded circuits, sensors, actuators, input and/or output devices, network and/or communication resources, memory resources of any type, processing resources of any type, and/or hardware devices configured to be responsive to determined conditions to functionally execute one or more operations of systems and methods herein.

Network and/or communication resources include, without limitation, local area network, wide area network, wireless, internet, or any other known communication resources and protocols. Example and non-limiting hardware and/or computing devices include, without limitation, a general purpose computer, a server, an embedded computer, a mobile device, a virtual machine, and/or an emulated computing device. A computing device may be a distributed resource included as an aspect of several devices, included as an interoperable set of resources to perform described functions of the computing device, such that the distributed resources function together to perform the operations of the computing device. In certain embodiments, each computing device may be on separate hardware, and/or one or more hardware devices may include aspects of more than one computing device, for example as separately executable instructions stored on the device, and/or as logically partitioned aspects of a set of executable instructions, with some aspects comprising a part of one of a first computing device, and some aspects comprising a part of another of the computing devices.

A computing device may be part of a server, client, network infrastructure, mobile computing platform, stationary computing platform, or other computing platform. A processor may be any kind of computational or processing device capable of executing program instructions, codes, binary instructions and the like. The processor may be or include a signal processor, digital processor, embedded processor, microprocessor or any variant such as a co-processor (math co-processor, graphic co-processor, communication co-processor and the like) and the like that may directly or indirectly facilitate execution of program code or program instructions stored thereon. In addition, the processor may enable execution of multiple programs, threads, and codes. The threads may be executed simultaneously to enhance the performance of the processor and to facilitate simultaneous operations of the application. By way of implementation, methods, program codes, program instructions and the like described herein may be implemented in one or more threads. The thread may spawn other threads that may have assigned priorities associated with them; the processor may execute these threads based on priority or any other order based on instructions provided in the program code. The processor may include memory that stores methods, codes, instructions and programs as described herein and elsewhere. The processor may access a storage medium through an interface that may store methods, codes, and instructions as described herein and elsewhere. The storage medium associated with the processor for storing methods, programs, codes, program instructions or other type of instructions capable of being executed by the computing or processing device may include but may not be limited to one or more of a CD-ROM, DVD, memory, hard disk, flash drive, RAM, ROM, cache and the like.

A processor may include one or more cores that may enhance speed and performance of a multiprocessor. In embodiments, the process may be a dual core processor, quad core processors, other chip-level multiprocessor and the like that combine two or more independent cores (called a die).

The methods and systems described herein may be deployed in part or in whole through a machine that executes computer readable instructions on a server, client, firewall, gateway, hub, router, or other such computer and/or networking hardware. The computer readable instructions may be associated with a server that may include a file server, print server, domain server, internet server, intranet server and other variants such as secondary server, host server, distributed server and the like. The server may include one or more of memories, processors, computer readable transitory and/or non-transitory media, storage media, ports (physical and virtual), communication devices, and interfaces capable of accessing other servers, clients, machines, and devices through a wired or a wireless medium, and the like. The methods, programs, or codes as described herein and elsewhere may be executed by the server. In addition, other devices required for execution of methods as described in this application may be considered as a part of the infrastructure associated with the server.

The server may provide an interface to other devices including, without limitation, clients, other servers, printers, database servers, print servers, file servers, communication servers, distributed servers, and the like. Additionally, this coupling and/or connection may facilitate remote execution of instructions across the network. The networking of some or all of these devices may facilitate parallel processing of program code, instructions, and/or programs at one or more locations without deviating from the scope of the disclosure. In addition, all the devices attached to the server through an interface may include at least one storage medium capable of storing methods, program code, instructions, and/or programs. A central repository may provide program instructions to be executed on different devices. In this implementation, the remote repository may act as a storage medium for methods, program code, instructions, and/or programs.

The methods, program code, instructions, and/or programs may be associated with a client that may include a file client, print client, domain client, internet client, intranet client and other variants such as secondary client, host client, distributed client and the like. The client may include one or more of memories, processors, computer readable transitory and/or non-transitory media, storage media, ports (physical and virtual), communication devices, and interfaces capable of accessing other clients, servers, machines, and devices through a wired or a wireless medium, and the like. The methods, program code, instructions, and/or programs as described herein and elsewhere may be executed by the client. In addition, other devices required for execution of methods as described in this application may be considered as a part of the infrastructure associated with the client.

The client may provide an interface to other devices including, without limitation, servers, other clients, printers, database servers, print servers, file servers, communication servers, distributed servers, and the like. Additionally, this coupling and/or connection may facilitate remote execution of methods, program code, instructions, and/or programs across the network. The networking of some or all of these devices may facilitate parallel processing of methods, program code, instructions, and/or programs at one or more locations without deviating from the scope of the disclosure. In addition, all the devices attached to the client through an interface may include at least one storage medium capable of storing methods, program code, instructions, and/or programs. A central repository may provide program instructions to be executed on different devices. In this implementation, the remote repository may act as a storage medium for methods, program code, instructions, and/or programs.

The methods and systems described herein may be deployed in part or in whole through network infrastructures. The network infrastructure may include elements such as computing devices, servers, routers, hubs, firewalls, clients, personal computers, communication devices, routing devices and other active and passive devices, modules, and/or components as known in the art. The computing and/or non-computing device(s) associated with the network infrastructure may include, apart from other components, a storage medium such as flash memory, buffer, stack, RAM, ROM and the like. The methods, program code, instructions, and/or programs described herein and elsewhere may be executed by one or more of the network infrastructural elements.

The methods, program code, instructions, and/or programs described herein and elsewhere may be implemented on a cellular network having multiple cells. The cellular network may either be frequency division multiple access (FDMA) network or code division multiple access (CDMA) network. The cellular network may include mobile devices, cell sites, base stations, repeaters, antennas, towers, and the like.

The methods, program code, instructions, and/or programs described herein and elsewhere may be implemented on or through mobile devices. The mobile devices may include navigation devices, cell phones, mobile phones, mobile personal digital assistants, laptops, palmtops, netbooks, pagers, electronic books readers, music players and the like. These devices may include, apart from other components, a storage medium such as a flash memory, buffer, RAM, ROM and one or more computing devices. The computing devices associated with mobile devices may be enabled to execute methods, program code, instructions, and/or programs stored thereon. Alternatively, the mobile devices may be configured to execute instructions in collaboration with other devices. The mobile devices may communicate with base stations interfaced with servers and configured to execute methods, program code, instructions, and/or programs. The mobile devices may communicate on a peer to peer network, mesh network, or other communications network. The methods, program code, instructions, and/or programs may be stored on the storage medium associated with the server and executed by a computing device embedded within the server. The base station may include a computing device and a storage medium. The storage device may store methods, program code, instructions, and/or programs executed by the computing devices associated with the base station.

The methods, program code, instructions, and/or programs may be stored and/or accessed on machine readable transitory and/or non-transitory media that may include: computer components, devices, and recording media that retain digital data used for computing for some interval of time; semiconductor storage known as random access memory (RAM); mass storage typically for more permanent storage, such as optical discs, forms of magnetic storage like hard disks, tapes, drums, cards and other types; processor registers, cache memory, volatile memory, non-volatile memory; optical storage such as CD, DVD; removable media such as flash memory (e.g. USB sticks or keys), floppy disks, magnetic tape, paper tape, punch cards, standalone RAM disks, Zip drives, removable mass storage, off-line, and the like; other computer memory such as dynamic memory, static memory, read/write storage, mutable storage, read only, random access, sequential access, location addressable, file addressable, content addressable, network attached storage, storage area network, bar codes, magnetic ink, and the like.

Certain operations described herein include interpreting, receiving, and/or determining one or more values, parameters, inputs, data, or other information (“receiving data”). Operations to receive data include, without limitation: receiving data via a user input; receiving data over a network of any type; reading a data value from a memory location in communication with the receiving device; utilizing a default value as a received data value; estimating, calculating, or deriving a data value based on other information available to the receiving device; and/or updating any of these in response to a later received data value. In certain embodiments, a data value may be received by a first operation, and later updated by a second operation, as part of the receiving a data value. For example, when communications are down, intermittent, or interrupted, a first receiving operation may be performed, and when communications are restored an updated receiving operation may be performed.

Certain logical groupings of operations herein, for example methods or procedures of the current disclosure, are provided to illustrate aspects of the present disclosure. Operations described herein are schematically described and/or depicted, and operations may be combined, divided, re-ordered, added, or removed in a manner consistent with the disclosure herein. It is understood that the context of an operational description may require an ordering for one or more operations, and/or an order for one or more operations may be explicitly disclosed, but the order of operations should be understood broadly, where any equivalent grouping of operations to provide an equivalent outcome of operations is specifically contemplated herein. For example, if a value is used in one operational step, the determining of the value may be required before that operational step in certain contexts (e.g. where the time delay of data for an operation to achieve a certain effect is important), but may not be required before that operation step in other contexts (e.g. where usage of the value from a previous execution cycle of the operations would be sufficient for those purposes). Accordingly, in certain embodiments an order of operations and grouping of operations as described is explicitly contemplated herein, and in certain embodiments re-ordering, subdivision, and/or different grouping of operations is explicitly contemplated herein.

The methods and systems described herein may transform physical and/or or intangible items from one state to another. The methods and systems described herein may also transform data representing physical and/or intangible items from one state to another.

The methods and/or processes described above, and steps thereof, may be realized in hardware, program code, instructions, and/or programs or any combination of hardware and methods, program code, instructions, and/or programs suitable for a particular application. The hardware may include a dedicated computing device or specific computing device, a particular aspect or component of a specific computing device, and/or an arrangement of hardware components and/or logical circuits to perform one or more of the operations of a method and/or system. The processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory. The processes may also, or instead, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as a computer executable code capable of being executed on a machine readable medium.

The computer executable code may be created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and computer readable instructions, or any other machine capable of executing program instructions.

Thus, in one aspect, each method described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices, performs the steps thereof. In another aspect, the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware. In another aspect, the means for performing the steps associated with the processes described above may include any of the hardware and/or computer readable instructions described above. All such permutations and combinations are intended to fall within the scope of the present disclosure.

While the disclosure has been disclosed in connection with certain embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present disclosure is not to be limited by the foregoing examples, but is to be understood in the broadest sense allowable by law. 

What is claimed is:
 1. A system, comprising: a polarization birefringence grating (PBG) interposed between an electromagnetic (EM) source and a first volume hologram; the first volume hologram interposed between the PBG and a second volume hologram; the second volume hologram interposed between the first volume hologram and a continuous steering element; wherein the continuous steering element comprises: a high-side electrode layer comprising: a first plurality of electrical members alternated with, and electrically coupled to adjacent ones of a second plurality of electrical members; wherein one of the first plurality of electrical members or the second plurality of electrical members comprises a plurality of discrete electrodes; and wherein the other one of the first plurality of electrical members or the second plurality of electrical members comprises a plurality of resistors; a low-side electrode layer; and an electro-optic (EO) layer comprising an EO active material at least partially interposed between the high-side electrode layer and the low-side electrode layer, thereby forming a plurality of active cells of the EO layer; wherein the PBG is responsive to a polarization of an incident beam from the EM source to selectively steer the incident beam to one of a first selected angle or a second selected angle; wherein the first volume hologram is responsive to the first selected angle of the incident beam to increase a steered angle of the incident beam in a direction of the first selected angle; and wherein the second volume hologram is responsive to the second selected angle of the incident beam to increase the steered angle in a direction of the second selected angle.
 2. The system of claim 1, further comprising: a controller, comprising: a steering request circuit structured to interpret a steering request value; a steering configuration circuit structured to determine a plurality of EO command values in response to the steering request value, and wherein the plurality of EO command values correspond to a half-wave voltage profile; and a steering implementation circuit structured to provide a plurality of voltage commands in response to the plurality of EO command values.
 3. The system of claim 2, wherein the half-wave voltage profile comprises: a first voltage value for a last electrode of a first phase delay progression, the last electrode comprising one of the plurality of discrete electrodes; a second voltage value for a first electrode of a second phase delay progression, the first electrode comprising one of the plurality of discrete electrodes; and wherein the first voltage value and the second voltage value have opposite signs.
 4. The system of claim 3, wherein the first voltage value and the second voltage value have equal magnitudes.
 5. The system of claim 3, wherein the first voltage value and the second voltage value have magnitudes that differ by a voltage difference corresponding to an nπ phase delay, wherein n comprises an integer value between 1 and 4, inclusive.
 6. The system of claim 1, wherein the low-side electrode layer comprises a second plurality of discrete electrodes.
 7. The system of claim 1, wherein the low-side electrode layer comprises a continuous electrode.
 8. The system of claim 1, wherein the low-side electrode layer comprises a reflective layer.
 9. The system of claim 1, further comprising: a convex lens portion optically coupled to the continuous steering element on a first side of the continuous steering element; and a concave lens portion optically coupled to the continuous steering element on a second side of the continuous steering element.
 10. The system of claim 9, wherein the thin beam steering device and the associated fishtail booster comprise a combined steering capability of greater than 25 degrees.
 11. The system of claim 9, wherein the system comprises a final steering capability of greater than 30 degrees.
 12. The system of claim 9, wherein the system comprises a final steering capability of greater than 45 degrees.
 13. The system of claim 9, wherein the system comprises a final steering capability of between 45 degrees and 60 degrees, inclusive.
 14. The system of claim 9, wherein the system comprises a final steering capability of greater than 60 degrees.
 15. The system of claim 1, further comprising: a steering controller, comprising: a steering request circuit structured to interpret a steering request value; a steering configuration circuit structured to determine a plurality of electro-optical command values in response to the steering request value; and wherein the continuous steering element is responsive to the plurality of EO command values to provide a corresponding phase delay progression across the continuous steering element.
 16. The system of claim 15, further comprising: wherein the steering configuration circuit is further structured to determine a polarization orientation in response to the steering request value; and a selectively polarized electromagnetic source structured to provide the incident beam to the PBG at a selected one of a first polarization corresponding to the first selected angle, or a second polarization corresponding to the second selected angle, and wherein the selectively polarized electromagnetic source is responsive to the polarization orientation. 